update travis.yml to do multi-ghc approach

updating travis.yml file for async package to build on test on the GHC 7.0 through 7.8.3 and GHC HEAD
bump version bounds on base
temporarily disable test suite to isolate whats not building with GHC HEAD
To make things nicer
removing the lines because travis was getting confused
Merge pull request #23 from cartazio/patch-1

update travis.yml to do multi-ghc approach + bump bounds