Initial draft: 0.7.0

[cgewecke]

#346 Swaps event-based instrumentation w/ testrpc-sc for variable-based instrumentation processed by a generic ganache VM listener. (This PR targets the next branch.)

The changes here are less extensive than they might seem at first glance. All the core instrumentation logic has been retained and should be +/- recognizable.

Summary

• modify injector to use variable definitions and assignment statements we can read with an opcode tracer.
• add DataCollector class which listens to the VM for data-hash-detected-on-stack 'events'
• rename instrumentSolidity --> Instrumenter & make JS class / top level controller
• rename instrumenter --> Registrar & make JS class. (annoying...best name I could think of)
• remove pure/view preprocessing
• mark instrumentation hits in memory / transform to coverage object from memory
• refactor test suite for this design