Specify python cookbook version in Berksfile

The current version of the python cookbook requires yum-epel which
requires yum ~3. Until the stackforge cookbooks that use the yum
cookbook are updated, we must use the last version of that python
cookbook that is compatible with yum 2.3.4, which is python 1.4.4.

Change-Id: If72449a0965164490da3d2103622d4b6eecf1626
Closes-Bug: #1273714