Proposed fix for #177. This does have the downside that it would
immediately require text-1.1, which might cause for some people
committed to older versions of the Haskell Platform.
Fix cabal-install for GHC 7.8; better support for GHC < 7.8
In retrospect, this does require a version bump to 0.7.1.0.
This doesn't work for me, as when it tries to build bytestring-builder, that package gets its own configuration wrong and builds nothing.