Updates nupic.core to c3dc7b8affa8162a85dc8c77cd6dadee84d79e90.
Removes parallel unit tests.

Fixes #1147.
Merge pull request #1221 from numenta-ci/core-update-sha

Updates nupic.core to latest built SHA.
Merge pull request #1226 from rhyolight/remote-parallel-unit-tests

Removes parallel unit tests.
Merge remote-tracking branch 'origin/master' into wrapAroundOff
Updated the doc string for _mapPotential.