[WIP] Testing refactors

[djrtwo]

• [ ] move protocol specific tests into tests/casper/*protocol_name*
• [ ] refactor testing to be generic where possible, and to test specific protocols where doing so
• [ ] Maybe provide minimum implementations of most methods on the abstract classes (message and view) so that generic tests can pass
• [ ] make testlang protocol agnostic
• [ ] pass in protocol as a param to casper.py
• [ ] require specify protocol in experiment .json file
• [ ] Will have to make a specific analyzer to each protocol. i.e. BlockchainAnalyzer