require newer version of pyrax

There are critical upstream bugfixes that are in pyrax 1.9
Most importantly, celery processes are long-lived days on end, but pyrax
auth was timing out at 24 hours, causing auth issues.
Merge pull request #166 from rizumu/upgrade-pyrax

require newer version of pyrax
greater than OR equal to 1.9
Merge pull request #167 from rizumu/upgrade-pyrax

greater than OR equal to 1.9