add celery_work_dir and more tests
fixes for python 2.6
CFY-1468 fix
Update dev-requirements.txt
Merge pull request #6 from cloudify-cosmo/CFY-1468-python26-support

Cfy 1468 python26 support
Merge branch 'master' into CFY-1318-tosca-interfaces

Conflicts:
	dev-requirements.txt