MAINT: Remove deprecated importall.

The importall function was the only function in the numpytest.py
file, so remove the whole file.
DOC: Update the release notes.

Remove duplicated "New Features" heading.
Note removal of numpytesting.py file containing importall function.
MAINT:Ignore boolean '-' deprecation warnings in nosetester.py

This allows numpy 1.9 testing to be used with current scipy
without flooding the output with deprecation warnings.

The deprecation warnings are currently issued for both the
subtract and negative operators when used with booleans.
DOC: update 1.9.0-notes.
Merge pull request #4680 from charris/pre-1.9.x-branch

Pre 1.9.x branch