rev bundler to latest
Add appbundler so we can generate bins with it
Remove outdated auxilary gem statements

* net-ssh-multi and highline are in Chef's gemspec, don't need to
  install them separately.
* ruby-shadow works on Mac OS X and FreeBSD now.
Install Chef to the default gem bin directory

A separate step will be added to generate appbundler executables for
Chef.
Install berkshelf to regular gem bindir

We'll appbundler the binaries...
Move test-kitchen to its own software defn
Switch berks and tk to git-based installs
`-static-libgcc` doesn't work on Mac

It's not clear why this was used in the first place. `git blame` pointed
at Adam J, but he didn't remember. I thought this might be required on
linux but I was able to successfully build on Ubuntu without this
option.
Install berks and TK from git and appbundle them
Remove ENV vars for tk and berks versions

In the past we used these to facilitate building specific branches/tags
in jenkins using build parameters, but now we're going to a create a new
branch of omnibus-chef when we need to do this.
Merge branch 'appbundle-chef-berks-tk'

* Berks and TK installed from git
* Chef, Berks, and TK now have executables in the "main" bin/ directory
  generated by appbundler.