Added Python-2.6 to the classifier.
Added Python-2.6 to the classifier.

OpenStack is often used with dustributions of GNU/Linux
which use python-2.6 as a default python interpreter.
Other OpenStack projects declare compatibility with python-2.6.

Ironic is been continuously tested for compatibility with
python-2.6 so we must declare this in the classifier to
stay synced with other OpenStack services.

Change-Id: Idf296e925c39d2847e7c8d7bfca073b5f9681754

rdo-management/ironic,naototty/vagrant-lxc-ironic,Tan0/ironic,ramineni/myironic,ionutbalutoiu/ironic,pshchelo/ironic,dims/ironic,redhat-openstack/ironic,varunarya10/ironic,bacaldwell/ironic,NaohiroTamura/ironic,devananda/ironic,ionutbalutoiu/ironic,openstack/ironic,dims/ironic,froyobin/ironic,bacaldwell/ironic,JioCloud/ironic,hpproliant/ironic,naterh/ironic,faizan-barmawer/openstack_ironic,SauloAislan/ironic,citrix-openstack-build/ironic,naototty/vagrant-lxc-ironic,pshchelo/ironic,openstack/ironic,supermari0/ironic,SauloAislan/ironic,citrix-openstack-build/ironic,debayanray/ironic_backup,rackerlabs/ironic,NaohiroTamura/ironic,Tehsmash/ironic