Upload custom java and python libraries

[nynymike]

Customers may want to upload custom java (jars) and python classes to use in their interception scripts. This is important, as we want to minimize the code in the scripts. These libraries need to be available for CE, CN and Snap. So it would be best if the interface to storage and loading the libraries is abstracted, and then we can make implementations for CN, CE, and Snap.