remove python 2.6 trove classifier
remove python 2.6 trove classifier

OpenStack projects are no longer being tested under Python 2.6, so
remove the trove classifier implying that this project supports 2.6.

Change-Id: I5deb330ac5eb7aaff846eaf41aa2c036926aad5e

stackforge/fuel-dev-tools,stackforge/fuel-dev-tools,stackforge/fuel-dev-tools