get_path(dependency)
Instance Public methods
Return the full path to the cached gem file matching the given name and
version requirement. Returns 'nil' if no match.
Example:
get_path 'rake', '> 0.4' # "/usr/lib/ruby/gems/1.8/cache/rake-0.4.2.gem"
get_path 'rake', '< 0.1' # nil
get_path 'rak' # nil (exact name required)