Create a proposal template. (#423)

* Create a proposal template.

Also update CONTRIBUTING.md to mention use of proposals

CONTRIBUTING.md

@@ -31,6 +31,7 @@ are very busy and read the mailing lists.
 
 This is a rough outline of what a contributor's workflow looks like:
 
+- Create a proposal (if neccessary - see below) and get an LGTM by someone in [maintainer](MAINTAINERS)
 - Create a topic branch from where you want to base your work (usually master).
 - Make commits of logical units.
 - Make sure your commit messages are in the proper format (see below).
@@ -40,6 +41,18 @@ This is a rough outline of what a contributor's workflow looks like:
 
 Thanks for your contributions!
 
+## Proposals
+
+For very simple contributions - bug fixes, documentation tweaks, small optimizations, etc. - a proposal is not neccesary. Otherwise, it's necessary to discuss your proposal with other members of the community and get approval from the maintainers. 
+
+To create a proposal, copy the markdown from the [proposal template](PROPOSAL_TEMPLATE.md) and put it in the relevant issue. Once you've gotten an LGTM from a [maintainer](MAINTAINERS), you can proceed with putting together a PR.
+
+Don't worry if you're proposal is not accepted right away; you'll probably need to make some changes, depending on the scope of the proposal.
+
+Here's a link which creates a new issue populated with the proposal link:
+
+[Create a Proposal](https://github.com/coreos/dex/issues/new?body=Proposal%0A%3D%3D%3D%0A%0A%28Feel%20free%20to%20change%20headings%20here%2C%20remove%20sections%20that%20are%20not%20relevant%2C%20or%20add%20other%20sections%29%0A%0A%23%23%20Background%0A%0ADescribe%20what%20problem%20is%20being%20solved%20here%2C%20and%20%28briefly%29%20how%20this%20proposal%20solves%20it.%0A%0A%23%23%20Data%20Model%0A%0ADescribe%20the%20logical%20data%20model%20that%20your%20proposal%20adds.%0A%0A%23%23%20Data%20Storage%0A%0ADescribe%20how%20the%20data%20will%20be%20persisted.%0A%0A%23%23%20API%0A%0ADescribe%20the%20methods%20that%20the%20API%20will%20expose.%20If%20there%20are%20any%20breaking%20changes%20be%20sure%20to%20call%20them%20out%20here.%0A%0A%23%23%20UI/UX%0A%0AIs%20there%20a%20front-end%20component%20to%20this%20work%3F%0A%0A%23%23%20Implementation%0A%0AHere%20is%20where%20you%20can%20go%20into%20detail%20about%20implementation%20details%20like%20data%20structures%2C%20algorithms%2C%20etc.%0A%0A%23%23%20Security%0A%0AWhat%20are%20the%20security%20implications%20of%20this%20proposal%3F%20How%20are%20API%20requests%20authenticated%3F%20Who%20can%20make%20API%20calls%3F%0A%0A%23%23%20OIDC/OAUTH2%0A%0ADoes%20this%20feature%20relate%20to%20any%20spec%3F%20%0A%0A%23%23%20Risks/Alternatives%20Considered%0A%0AWhat%20are%20the%20downsides%20to%20this%20implementation%3F%20What%20other%20alternatives%20were%20considered%3F%0A%0A%23%23%20References%0A%0AIf%20there%27s%20any%20references%20or%20prior%20art%2C%20put%20that%20here.)
+
 ### Format of the Commit Message
 
 We follow a rough convention for commit messages that is designed to answer two

PROPOSAL_TEMPLATE.md

+Proposal
+===
+
+(Feel free to change headings here, remove sections that are not relevant, or add other sections)
+
+## Background
+
+Describe what problem is being solved here, and (briefly) how this proposal solves it.
+
+## Data Model
+
+Describe the logical data model that your proposal adds.
+
+## Data Storage
+
+Describe how the data will be persisted.
+
+## API
+
+Describe the methods that the API will expose. If there are any breaking changes be sure to call them out here.
+
+## UI/UX
+
+Is there a front-end component to this work?
+
+## Implementation
+
+Here is where you can go into detail about implementation details like data structures, algorithms, etc.
+
+## Security
+
+What are the security implications of this proposal? How are API requests authenticated? Who can make API calls?
+
+## OIDC/OAUTH2
+
+Does this feature relate to any spec? 
+
+## Risks/Alternatives Considered
+
+What are the downsides to this implementation? What other alternatives were considered?
+
+## References
+
+If there's any references or prior art, put that here.

proposal_link

+#!/bin/bash -e
+
+# This creates a URL which will pre-populate an issue with the contents of PROPOSAL_TEMPLATE.md
+
+BODY=$(python -c "import urllib, sys; print urllib.quote(sys.stdin.read()[0:-1])" < PROPOSAL_TEMPLATE.md)
+
+echo "https://github.com/coreos/dex/issues/new?body=$BODY"