Issue #292 Update the build system to cmake and integrate it with Heka

- Migrated the current build functionality and extended in the following ways:
    - protobuf generation
    - yacc message parser generation
    - mock generation and dependency analysis
    - better prerequisite testing and version checking
    - improved support for 3rd party plugin integration
- Tested on Ubuntu, OSX, and Win7

FYI: The current directory structure was left intact even though Heka will not be Go 'gettable' any time in the near future.  The intent is to migrate to the new build system with minimal impact and then evolve it.