Renames 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: Iac3c680dd19cabd8ea38598a6e2bb27238030a2d
Fixes: bug #1179008
Merge "Renames tools/pip-requires to requirements.txt"