Add Coveralls.
Connection factory was ignored when cursor was created. Baed on jzlatov's pull request.
Added extra checks for a closed pool.
Initializing a pool will now call the callback also when an error occurs.
This allows the caller to try to setup the pool again later.
Removed wrong argument.
Merge branch 'failed-pool-init' into develop
Added test for pool initialization exception.
Merge branch 'develop'

Conflicts:
	momoko/connection.py