- added caveats to unittest README encountered with Py2.7 + current nose 0.11.3
- call counts for py2.7. all tests pass for sqlite + mysql-python + psycopg2
defined bind parameter name that directly conflicts with
a column-named bind generated directly from the SET or
VALUES clause of an update/insert generates a compile error.
This reduces call counts and eliminates some cases where
undesirable name conflicts could still occur.