Rename pywin-* test envs to py-*-w32
Run tests at AppVeyor with Python-x64
Remove the list of test dirs from mssql-w32 tox...
Rename win* tox envs to *-w32
Run Pg and SQLite tests with Py3.5-win
Run tests at AppVeyor with MySQL
Run createdb/dropdb with option -w
Remove pg8000 driver