In test-suites and benchmarks, depend on source

Depend directly on the source of binary, instead of the library itself.
This is unfortunate as it complicates the cabal file, but we have to in
order to remove circular dependencies when installing dependencies of
the test-suites and benchmarks.
binary.cabal: update list with which GHCs we've tested
Update .gitignore and .hgignore with cabal sandbox files
Version bump to 0.7.2.0
First attempt at adding Travis CI support.