Adding patch validation

[rhysrevans3]

Added validation for patch requests:

• Convert operations to partial Item.
• Deny move or copy operations. This might need to be made more lenient if we need move for alternate asset updates.
• Added expected extensions on a per collection basis. With defaults and regexes. (currently through settings but could be a service)
• Validate against expected extensions. (ignore required errrors)

closes #22

[sturoscy-personal]

Going ahead and approving this so we can keep moving forward. Will run locally and hopefully get a dev/test instance running in AWS space.

[sturoscy-personal]

Thought I had approved this already. Looks good. Thank you!

[sturoscy-personal]

Thanks Rhys for the work. Approving to move work forward.