Adds python 2.6 and bigip 12.1.2 to tox file
Adds python 2.6 and bigip 12.1.2 to tox file

Issues:
Fixes #825

Problem:
python 2.6 and bigip 12.1.2 are not available in the tox file

Analysis:
this patch adds support for both of these

Tests:

F5Networks/f5-common-python,F5Networks/f5-common-python