Use universal rubygems method for installing gems
Use universal rubygems method for installing gems

The current implementation for installing gems via `rake spec:deps`
builds a rubygems command that includes all of the gems in a single
oneliner with gem names and versions that are colon delimited:

    $ ruby -S gem install --no-ri --no-rdoc --conservative 'automatiek:~> 1.0.0' 'mustache:0.99.6' ...

This functionality does not exist prior to rubygems 2.0, so this will
not function with the rubygems that ships with ruby 1.9.3

Splitting this into individual `ruby -S gem install` calls for rubygems
versions prior to 2.0, and using the `-v` flag allows this to function
on older implemetations.

mvz/bundler,mvz/bundler,dilumnavanjana/bundler,dilumnavanjana/bundler,bundler/bundler,bundler/bundler