Update dependencies to latest versions

Incorporates the latest version of base so that
the package will build with GHC 7.8.  This also
required removing Template Haskell from the tests;
it was causing problems with GHC 7.8--sometimes it
would not compile at all; other times, it would
compile but the test binary would do nothing.

The tests now use Tasty.
Test balances for associativity

Currently balances are not associative.  This
violates the monoid laws.  Fixing this will take a
fair amount of work.