Adds `--tiller-namespace` flag and `TILLER_NAMESPACE` envvar
to use tiller in an alternate namespace.

closes #1418

Downloading of charts and helm itself happened over http. This
change moves to use https as that is available with valid certs.

A bucket name in the path can be migrated to a custom k8s domain
name. This is in preperation for that.

This adds documentation for 'scripts/get'.

This provides an example of an in-place upgrade to Tiller using `kubectl
set image`.

Fixes #1393

This refreshes docs, as discussed in #719, and adds a few new sections
to the docs.

Closes #719

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. :)

This includes documentation on how to use Helm and Tiller canary
releases.