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.

README: move history to docs/history.md

ref(helm): simplify tunnel tests

fix(tiller): re-enable skipped test, golint, & gofmt all the things

feat(rollback storage): support for rolling back to previous release.

feat(helm): add optional version flag to helm{get,status}

The history is helpful for people who have never heard of helm but I
don't think it is super relevant for most users.

fix(helm): avoid a panic for sign

Provide concrete information about who to contact about CoC issues. Having unambiguous people to contact is important to resolve issues in a timely manner.

This is the primary important change, having consistent and explicit
points of contact: https://github.com/kubernetes/kubernetes-template-project/commit/98749d6b8efc612fe05d1bc42b0e0bff89f30e0a

Before this fix:

```
 /Users/philips/src/k8s.io/helm/bin/helm package --sign mychart --key FC8A365E
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x13120a]

goroutine 1 [running]:
panic(0x10fed00, 0xc4200120d0)
       	/usr/local/Cellar/go/1.7.1/libexec/src/runtime/panic.go:500 +0x1a1
k8s.io/helm/pkg/provenance.(*Signatory).ClearSign(0xc4205db100, 0xc42011ec20, 0x20, 0x8, 0xc4205db100, 0x0, 0x0)
       	/Users/philips/src/k8s.io/helm/pkg/provenance/sign.go:156 +0x3a
main.(*packageCmd).clearsign(0xc420017720, 0xc42011ec20, 0x20, 0x0, 0x0)
       	/Users/philips/src/k8s.io/helm/cmd/helm/package.go:143 +0xa5
main.(*packageCmd).run(0xc420017720, 0xc420390240, 0xc420120d00, 0x1, 0x4, 0x13639b0, 0x104dfe0)
       	/Users/philips/src/k8s.io/helm/cmd/helm/package.go:130 +0x31b
main.newPackageCmd.func1(0xc420390240, 0xc420120d00, 0x1, 0x4, 0x0, 0x0)
       	/Users/philips/src/k8s.io/helm/cmd/helm/package.go:77 +0xc4
k8s.io/helm/vendor/github.com/spf13/cobra.(*Command).execute(0xc420390240, 0xc420120c40, 0x4, 0x4, 0xc420390240, 0xc420120c40)
       	/Users/philips/src/k8s.io/helm/vendor/github.com/spf13/cobra/command.go:571 +0x234
k8s.io/helm/vendor/github.com/spf13/cobra.(*Command).ExecuteC(0xc420405200, 0x0, 0x0, 0x0)
       	/Users/philips/src/k8s.io/helm/vendor/github.com/spf13/cobra/command.go:661 +0x367
k8s.io/helm/vendor/github.com/spf13/cobra.(*Command).Execute(0xc420405200, 0x1b52720, 0xc4200001a0)
       	/Users/philips/src/k8s.io/helm/vendor/github.com/spf13/cobra/command.go:620 +0x2b
main.main()
       	/Users/philips/src/k8s.io/helm/cmd/helm/helm.go:110 +0x2d
```

fix(Makefile): cleanup _dist files

fix(lint): allow .txt files

closes #1161

feat(charts): add 'dependencies:' to Chart.yaml

fix(tiller): store failed release on post-inst failure