Move database_cleaner gem to test group

We only use this in our test environment, so I'm moving it to that group
to keep things orderly and fast.

Change-Id: I55635c366a1fc19deb008a21b0423cfb0e9fce3c
Move coveralls gem to test group

This gem is only used in our test environment so I am moving it to the
test group to keep things orderly and fast.

Change-Id: I2c7062b55ae536399ad446771c602acf85afffca