update select2 and chosen asset references for the asset pipeline

Making assets work.

RW + AJP
hi @bakis2011, I thought we should be able to make it work -without- modifying /vendor'd assets as well.  But alas, even `rake bower:resolve` touches the .css files, changing them to .css.erb and updating the url paths to the asset helper versions.   The automated rake task makes this a bit more bearable.