feat(helm): add requirements.yaml support

This also refactors significant portions of the CLI, moving much of the
shared code into a library.

Also in this release, a testing repository server has been added.

feat(*): add api version checks

ref(helm): convert repo commands to new format

issue #1203

fix(helm-list): filter configmaps by owner=TILLER

feat(repo): use OCI style digest identifiers

feat(*): add git tree state to binaries

README: add History to TOC and footer for CoC

Use the same format as the Open Container Initiative for a digest
string. https://github.com/opencontainers/image-spec/blob/master/descriptor.md#digests-and-verification

Fixes #1166

* clean up version output

first cut of version on client and server

fix(tiller): Upgrade shouldn't fail if there are no changes

clean up the formatting, remove unnecessary git_version from version as per discussions with @areese

Signed-off-by: Keerthan Reddy Mala (kmala) <kmala@deis.com>

fix(ci): fix typo in auth file reference

After d1488f1d I forgot to add this to
the TOC.

Lifted from https://raw.githubusercontent.com/kubernetes/kubernetes-template-project/master/README.md

code-of-conduct: use the upstream language

feat(README): add community contact points

feat(ci): build canary helm binaries using CI

README: fix small typo

Add the sig-apps mailing list, developer call details, and #helm slack
channel.

Based on https://github.com/kubernetes/kubernetes-template-project/blob/master/README.md

ref(helm): refactor checkArgsLength method

docs(README): remove the build from source instructions

fix(#1185): get release status by version iff version > 0

docs/developers.md already has these instructions. And 80% of the time
someone looking at this project is interested in getting started not
hacking directly.