More work on eliminating references to test_db_util.sa_session.

... tweaked styling of several functional tests (the non-toolbox,datamanager,workflow,api functional tests) along the way - mostly PEP-8 fixes and eliminating * imports. Did not modify tests which do not pass - but did not in the source where they fail inside a TODO.
WIP: Tool execution tests.
Initial work on functional tests for the tools API.

Just tests some simple indexing and tool execution. Tons more one can and should test.
Some PEP-8 fixes for api/tools.py.
Some PEP-8 fixes for tools/__init__.py.