Added routes for machines.  Also modified exzweight form to show exercise
machine type, model, and company.

TO DO:
- Next step is to make sure that user cannot enter combinations of type,
model, and company that are not in the database.  At least not without
being asked if they wish to add a new entry to machines.

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

 Changes to be committed:
	modified:   app/models/machine.rb
	modified:   app/views/exzweights/_form.html.erb
	modified:   config/routes.rb
	new file:   db/migrate/20140610200408_adapt_exzweights_to_machines.rb