[DPP-22] Relaxed base dependencies rules
[DPP-22] Relaxed base dependencies rules

Issue:
The Travis CI box is only capable of using GHC 7.4.1 and Base 4.5.0.0,
but the current cabal file requires base >= 4.8.

Outcome:
Changed the cabal file to accept a lower base library version.

simone-trubian/dropp,simone-trubian/dropp,simone-trubian/dropp