Remove magic import from sh module

Since the magic import "from sh import pip"
is harder to debug and has problems on some
systems, it is now substituted by a conventional
pip-command object creation.
Added Jens Kadenbach to contributors
Merge pull request #21 from audax/bugfix/sh-import

Fix import issues with the sh library
Allow new document version to be created without having to specify the document
Merge remote-tracking branch 'origin/master'
Enable token authentication for the API, add API token request view
Exclude the API urls from forced session based authentication
We now have token based authentication support too
Make sure the reponse has a Content-Type
Before trying to make sure it is an HTML response
or else it can causes errors in DELETE API responses
Add functional document API test
Bump version to 1.0 rc3
Update version in instructions
Don't waste time scanning the 'mayan/media' directory
Is not relevant for packaging and can cause slow execution
if ran from an existing installation
Don't include anythin in mayan/media