Brownju/bug/47

Added a module for validating user input, moved the location of orvsd_central.database.Model to orvsd_central.models.Model, and added tests to general.register() which the function itself still needs to be tested for correctness.
If/when the creation of the user fails I am not sure how I would go back and find out if it was because it was not unique, or if because it was a bad string. The way I have it now will result in a more descriptive error message to the input form.