Stop testing on PHP 5.2

This is the beginning of our PHP 5.2 support deprecation.
See also #1830
https://github.com/ginatrapani/ThinkUp/issues/1830
[DB MIGRATION REQ'D] Keep users logged in via long-term cookie

Adds tu_cookies table.
CookieDAO and MySQL Implementation.
Test for DAO.
Check for cookie when not isLoggedIn() in Session.
Kill cookie on logout.
Integration tests for login, and new one for logout.
Updates installer and DAOFactory tests.

Closes #388, closes #1832