Fix nondeterministic timeout in miner tests
Created by: mnsl
@DavidVorick's theory for issue #1107 (closed) is that the Travis short tests sometimes fail for the miner because Travis is too slow. If so, this pull request should resolve #1107 (closed) by skipping TestIntegrationNilMinerDependencies
and TestIntegrationBlocksMined
, the only two miner testing functions with significant I/O that were not already being skipped.