Update to latest rspec and stop requiring mocks separately.

@wycats @sferik 

I tried to `bundle install` and got this:

```
Fetching gem metadata from https://rubygems.org/.........
Fetching gem metadata from https://rubygems.org/..
You have requested:
  rspec-mocks >= 2.12.2
The bundle currently has rspec-mocks locked at 2.11.3.Try running `bundle update rspec-mocks`
```

This seems to have fixed it.