Fix text tests on some versions of Linux
Fix text tests on some versions of Linux

In particular, my local Ubuntu machine uses capitalized day/month
names, causing tests to fail. This normalizes that just for the sake
of tests.

Fixes #943.

malcolmr/nodatime,jskeet/nodatime,nodatime/nodatime,malcolmr/nodatime,nodatime/nodatime,BenJenkinson/nodatime,malcolmr/nodatime,malcolmr/nodatime,BenJenkinson/nodatime,jskeet/nodatime