Checking in Gemfile.lock

Our configuration seems to break often due to new gems being released (#1582, #1444, #1133, #1057). I would propose the following: We test out using Gemfile.lock and if that causes too much pain, then we remove it and instead specify better gem requirements in our Gemfile. 

Please test out this PR with hub (`hub checkout https://github.com/Katello/katello/pull/1584`) to make sure it works in your development setup. Be sure to back up your existing Gemfile.lock though! Thank you.

Alternatively to test out just the Gemfile.lock, go into your katello src directory and run:

```
mv Gemfile.lock Gemfile.lock.bak
curl -O https://raw.github.com/daviddavis/katello/e5ab58fe8a03d8718b0795b14b64c9f356f42217/src/Gemfile.lock
```