Feat - implement queue

[Jamesbarford]

This is a bit prototype-y at the moment however I thought it wise to get some early feedback as the main ideas are here.

I do have some the some questions that I though of while implementing the queue namely;

• Do we want to add a retry column? As it is theoretically possible for a machine to keep picking up a job that it failed to do
• How to handle a "release" build which I've hacked together and endpoint for
• How to allocate a machine uuid
• How to let a machine know what architecture it is on (could do a shell uname -a or something similar)?

I don't think the SQLite implementation would work at all as there is an assumption that there is a centralised database or database cluster that the whole system speaks to. I could be wrong but with the SQLite implementation it would create a version of the database local to the machine (presently 2) thus would not work. With that in mind I've not implemented anything to handle concurrent access to SQLite. The implementation, presently, is only useful for local development and perhaps tests?