Update the list of tested versions of GHC
Update benchmark framework
Get the silly benchmark framework and AesonEncode cooperating
Update perf numbers for the previous versions of the various libs

I want to be able to use this as a baseline to see how the new
versions of the libraries fare.

--HG--
extra : amend_source : 166f845a7d1d42ee33c646f6fa7034d853eefe60
Update performance numbers

This clearly shows that on this dataset, decoding is about 33%
faster than the previous release, while encoding is about twice as
fast. Nice!
Rework Python encode/decode benchmarks to work with harness