Resolves #536

Made changes to the helper, mixed the helper into the activities controller, adjusted some structure, and changed tests to get the api changes to work.

Now follow up: I added all the entire version information under the symbol :versions.  Even though the model structure works that way, because in this case it will always be only one version, I wanted to just put it all under version, but I realized that was being used, which pointed me to this:

(lines 127-149) https://github.com/rubygems/rubygems.org/blob/master/app/models/rubygem.rb


My gut reaction to this is:
1- this is where we probably should have made our change originally.
2- there is a lot more from Version being flattened into Rubygem than I previously thought.  This makes me think that I should flatten the whole thing (as we had started to do) rather than nest it (as we discussed).

Thoughts?

Also, I need to write more tests, but I wanted to hold off because of my uncertainty in direction.