Allow use of 'nodeenv' in the bootstrap script.
Install 'pip-python' instead of 'pip'.
`sh` doesn't support the `source` command.
Merge pull request #71 from kobotoolbox/allow-nodeenv

Allow nodeenv in bootstrap script.
send proper HTTP response when submission received
add proper trigger functionality, closes https://github.com/kobotoolbox/enketo-express/issues/68
Merge branch 'master' of https://github.com/kobotoolbox/enketo-express