Correct ruby-switch argument when using ruby<VERSION>-full

When setting `ruby::ruby_package => 'ruby1.9.1-full'` (or
`'ruby1.8-full`) the correct argument to `ruby-switch --set` is
`ruby1.9.1` (or `ruby1.8`), not the package name as is. Handle these two
cases explicitly when `ruby::switch` is set. Contains updated spec
tests.
simplify array handling

pass as argument to Array() constructor, rather than [@a].flatten.compact
This changes the default values for ruby_package and rubygems_package on ubuntu 1404.
Merge pull request #34 from wolfspyre/fix_ubuntu_1404

Change the defaults for ruby_package and rubygems_package on ubu 14.04
Merge pull request #33 from antaflos/switch_handle_full_package_names

Correct ruby-switch argument when using ruby<VERSION>-full
Merge pull request #32 from igalic/patch-1

simplify array handling