Unit Tests + CI Environment

[yeastplume]

Unit tests for everything:

-Testing output solutions against known solutions at various sizes, that can be run against new plugin implementations to test their outputs
-Load testing
-Plugin loading/unloading
-White box stress testing on the plugins themselves, to check for leaks and segfaults

Note there is some oddness with cargo testing in that loading and unloading DLLs seems to cause segfaults on exit with no obvious reason. We may perhaps have to use another testing strategy or here.

[yeastplume]

Some of these are in place now, but TravisCI is a very inadequate build environment for testing mining plugins, especially at full-strength cuckoo 30 due to memory and cpu constraints. Another strategy for CI testing mining will be needed.