Code review comment for lp:~edwin-grubbs/launchpad/bug-458169-distroseries-timeout

Summary
-------

Fixed timeout on https://launchpad.net/ubuntu/karmic
and https://launchpad.net/ubuntu/+milestone/ubuntu-9.10/+index.

Implementation details
----------------------

Cached the Distribution.serieses and Distribution.currentseries
properties.

Tests
-----

./bin/test -vv -t 'distribution-soyuz.txt|productseries-views.txt'

Demo and Q/A
------------

* Open https://staging.launchpad.net/ubuntu/karmic
    * Should not timeout.
* Open https://staging.launchpad.net/ubuntu/+milestone/ubuntu-9.10/+index.
    * Should not timeout.