Screwed up and removed id in exzbikes table, then realized that this was
a bad idea and put it back.  Also added a gem for composite primary
keys to be possibly used in exzweights.

 On branch master
 Your branch is up-to-date with 'origin/master'.

 Changes to be committed:
	modified:   Gemfile
	modified:   Gemfile.lock
	new file:   db/migrate/20140602161910_intro_pri_key.rb
	new file:   db/migrate/2014060216400_return_id.rb
	modified:   db/schema.rb