Rename requires files to standard names.

    Rename tools/pip-requires to requirements.txt and tools/test-requires
    to test-requirements.txt. These are standard files, and tools in the
    general world are growing intelligence about them.

Change-Id: If5c7080fea7c5ca5935b3c064e368cb837a9c16b
Fixes: bug #1179008
Merge "   Rename requires files to standard names."