Added reference to plugins

ref(helm): use new debug method to standardize debug output

chore(*): bump kubernetes to v1.6.2

chore(README.md): update zoom meeting link

ref(*): Regenerates protobuf files with protoc 3.2.0

Protoc was updated a little while ago and we are likely to get more
people using it. This should avoid weird merge conflicts and bump us
to the latest version

feat(tiller): add --net-host flag to 'helm init'

test(*): add tests for new tls support

Fix indent for defaultDeployment

Search constraint and Install/Upgrade default constraint

Validates chart-dir before running dependency list command

When 'helm init --net-host=true' is run, Tiller will be installed with access to the host network (net=host in Docker)

Closes #2222

Adds a testdata directory to hold tls certs at the root
of the project. The tests cover pkg/tlsutil, cmd/helm,
and cmd/helm/installer.

Closes #2289

Implementation of pluggable downloaders

Fixes issues/2276: helm dependency list hangs if run on large directory

It is now possible to create plugins with chart download capabilities for custom, non-http protocols.
Furthermore it is possible to reuse helm packages to implement alternative clients with these custom downloader functions.

Exposes repository-URLs as flags on helm init command

Expose tiller server metrics to prometheus

Fixes issues/2272

stable-repository-url is currently hard-coded for helm init,
so if a user wants to make a different intranet repository as stable repo,
only option left is to first do an init,
followed by repo delete and repo add.

chartutil create ingress example

clarify helm serve's intent

fix(tiller): ignore empty YAML documents during delete

A lot of community members are looking at `helm serve` as a production webserver to host their
charts. There are much better solutions out there like s3, wabs or gcs for cloud storage and
nginx, haproxy or apache for DIY dedicated web servers. Steering users in the right direction
will help users make the right decision when it comes to serving their charts in production.

Closes #2256

fix(helm): fix nil pointer in requirements.go

fix(scripts): don't include plugins for generating docs

docs(*): Add ci script to confirm docs are up to date with commits