use a shell for supervisor

this expands env variables correctly
Merge pull request #63 from pepijndevos/patch-1

use a shell for supervisor
Fix supervisord port-indexing. Add tests
Fix shell used in supervisord export
Add jinja dependency in coverage tests
Add jinja to travis build for export tests
Fix Jinja2 installation for Python 3.2
Clean up,  accept more Py3 versions on Jinja2-2.6
Merge pull request #68 from krallin/test-supervisord-export

Supervisord export tests + fixes