Contributing draft

The Contributing.md is now written for a second year student start out with the queue. But could also be used as a reference for a more experienced developer. It explains a few key concepts of web development and how they are done in the queue currently.

It also provides a sample workflow for implementing a new feature and the steps to take.

The section regarding submitting your code is completely unfinished, since most of the content here still needs to be decided.

Finally it includes two pictures in the repository, where do we actually want to store these?