Fix coveralls behaviour

Coveralls was exhibiting erratic behaviour, showing coverage for a total of only 6 files yet there are over 90 relevant files, and haphazardly showing alternating statistics (see this [comment](https://github.com/rapidftr/RapidFTR/pull/705#issuecomment-52401596), as well as [this one](https://github.com/rapidftr/RapidFTR/pull/706#issuecomment-52414394), and the screenshot below):

![screen shot 2014-09-08 at 3 54 23 pm](https://cloud.githubusercontent.com/assets/5906754/4185482/5ad66392-3757-11e4-8fb6-b70ecdb1abb7.png)

It appears that this was because in the `features/support/env.rb` we were requiring coveralls after some other application code had already been required