Log Message:
py-numexpr: updated to 2.7.0

Changes from 2.6.9 to 2.7.0
- The default number of 'safe' threads has been restored to the historical limit
  of 8, if the environment variable "NUMEXPR_MAX_THREADS" has not been set.
- Thanks to @eltoder who fixed a small memory leak.
- Support for Python 2.6 has been dropped, as it is no longer available via
  TravisCI.
- A typo in the test suite that had a less than rather than greater than symbol
  in the NumPy version check has been corrected thanks to dhomeier.
- The file `site.cfg` was being accidently included in the sdists on PyPi.
  It has now been excluded.