setup.py now installs MySQL-python as dependency

setup.py no longer imports PySQLPool which imports MySQLdb.
This allows running setup.py even if MySQLdb is not installed on the system.

For convenience, I added the update_version.sh script, if we ever need to bump the version and are too lazy to update 2 places :)

Also, pip seems to complain when requirements contain a dash.
Replacing it with an underscore fixes that.