Finishing tests for dbtype/dbname rules

 - Complete test_ctor_dbtype_hpss_ tests (and moved them to the DBIdb2Test
   class)
 - Make test_pep8 ignore emacs' .#* work files
 - In assertRaisesMsg(), report expected and got aligned on two lines to make
   it easy to see the differences.

Change-Id: Ie9dd0ada97e36f6213cc5da2213262026800b838