basestring, range, long, url*, parse*, unicode, html_unescape
also, remove some obsolete sys.version checks

Python 3.4 added new Enum types that enforce a value belonging to the
enumeration.
This commit retires our homemade enum and use Python's Enum type.
Python 2 compatibility is achieved with "enum34" package.

Housing and Calendar capabilities are updated to use those new enums.