Organize Gemfile
Organize Gemfile

This commit clusters gems and alphabetizes the lists. At the same time I
converted a hashrocket to Ruby 1.9 style syntax.

Change-Id: I973d8c5a968cdb76eea1af723d4756e460a74e84

kalw/diffux,kalw/diffux,diffux/diffux,kalw/diffux,diffux/diffux,diffux/diffux