Adding json serializer
document configuration stuffs
Begin work on implementing configuration interface
add note to readme
make config options actually do stuff
clarify the readme a bit
keep yaml as default cassette serializer to fix unit tests
start adding config tests
test cassette library dir
Added test to confirm whether cStringIO works
Let's do an instance/module-based API for serializers
change serializer API so it doesn't have to do file stuff
add tests for registering serializer
remove unused cassette in with statement
Don't save cassette when it hasn't been modified
Fix intermittent test failure due to http happening too fast
Update README and bump version
pep8 fixes