CRUD ODL python RESTconf tests

* move to python2.6 and python script refactoring
* fix xml
* add CRUD tests (flow, meter, group)

https://wiki.opendaylight.org/view/OpenDaylight_OpenFlow_Plugin::Python_test_scripts

Signed-off-by: Vaclav Demcak <vdemcak@cisco.com>
Change-Id: I3c8723dae0cbd1500f9fe318ec90115ff739f3db