Enable default responses of a data source.

Signed-off-by: Philipp Kant <philipp@infinipool.com>
Merge pull request #1 from kantp/master

Enable default responses of a data source.
Fix in dataFetchOrElse.

The cache ruined our day.
Merge pull request #2 from kantp/sideeffects

Fix in dataFetchOrElse.
Merge branch 'equivalent-requests' of git://github.com/kantp/Haxl into kantp-equivalent-requests

Conflicts:
	Haxl/Core/Monad.hs
Merge branch 'kantp-equivalent-requests'
Fixed a thunk leak in performFetches.

The statistics that are gathered here contained thunks (unless the debug
level is high enough to print them).  Forcing the roundstats list to
normal form fixes this.
Merge pull request #4 from kantp/thunkleak-roundstats

Fixed thunk leak in roundstats.