Revert "re-org gemfile assets group, part 2: everything that might go there"

This reverts commit 26a8f8c03b517fb85a04db3bf987022d3254c2a8.
Revert "moving gems to asset group, step 1: jquery-rails"

This reverts commit 8d39ee785f52356cc820784abae5e9fffdef5d3e.