Move requirements files to standard names.

Change-Id: Ia27def1cf04aae8fe6e9f19e965b0083638d2201
Move tests into package dir.

This keeps it consistent with the other heat projects, and gets us
away from having a global 'tests' package.

Change-Id: Ic41b5fc235df0fce0feecfe678f743621e379aec
Migrate test base classes to testtools.

This is in prep for testr changes, but also cleans up
several things in the tests where state could leak.

Change-Id: I7f53dcee2f1fcffb622dd475ea8cf433ce43dbb2