ref(scripts): use gometalinter for linters

fix(helm): make 'helm help' text punctuation consistent

ref(helm): remove old structure functions

Closes #1301

This replaces the old structure functions with the functions in
cmd/helm/helmpath.

Closes #1318

ref(repo): move urlJoin to the right package

I wrote urlJoin to fix URL joining, but I put it in the wrong place and
never used it. This moves it to the right place, and replaces the hacky
previous solution.

docs(README): update download information

fix(tiller): correct sort manifests by type

chore(ci): limit cross build targets

Closes #1313

Limit cross builds to linux/amd64 linux/386 darwin/amd64

fix(ci): fix ci builds reporting dirty repo

docs(install): Add reference to glide in install docs

Also, hg is required.

The user needs to get all of the way down to developers docs to
realize they need glide, but if you follow a user who doesn't
necessarily want to develop but wants to build from source, you'd
follow this path:
README -> Quick Start -> Releases -> . o O (Source doesn't work)
 -> Install
And then you'd realize that you need Glide.

This one-liner patch fixes that. :)

```
% ./helm version
Client: &version.Version{SemVer:"v2.0.0-alpha.5", GitCommit:"4de...", GitTreeState:"dirty"}
Server: &version.Version{SemVer:"v2.0.0-alpha.5", GitCommit:"4de...", GitTreeState:"dirty"}
```

fix(*): prevent testing package from being imported

Fix typo in chart docs

Fix docs regarding .Files.GetString and .Files.GetBytes

Prevent testing package from being imported into main application

After #1021 ` .Files.GetString` does not exist any more.

fix(ci): glide cache path

feat(helm): remove the requirement that fetch/install need version

more money, more problems

This removes the requirement that a fetch or install command must
explicitly state the version number to install. Instead, this goes to
the strategy used by OS package managers: Install the latest until told
to do otherwise.

Closes #1198

feat(ci): cache glide directory

The name for the default values file is `values.yaml` and not `.values.yaml`.

feat(ci): upload checksum with binary releases

closes #1214

fix(helm): resolve URLs and SemVers correctly

docs(spelling): Fix some random misspellings

The original dependency resolution did not correctly resolve version or
URL of a dependency. Version was tracked by filename, and URL was
assumed to be absolute. This fixes both of those.

Closes #1277

feat(helm): add --versions flag on search