Enhancing async access for courses with registered students

[etrickel]

New Code enhancing the container access that was recently pushed:

• Allows the launching of a container using a get instead of a post
• Creates student access tokens for a course, it will only generate an access token for students that have entered their student id
• The generated token starts with the dojo.id instead of workspace
• The new endpoint /dojo/<dojo>/admin/create_tokens also prints out the current tokens in json format
• It also has the fix for the create token adding datetime in there

These changes unintentionally got merged with the branch that had features from PR#513