Merge branch 'feature/Automated_ship_fit_matching', implements and closes #13.

Added fitting hash to ship fit entity and map.
Fitting hash generation method.
Added 'no match' ship fit images.
Removed contract items validation layer code.
Repository method to fetch a dictionary of ship fit hashes & their related fit ids.
Method to hash contract items and attempt a match with an existing ship fit.
Order invalid contracts to the bottom of the list.
Added the contract description data to the contract info tooltip.
Set the contract description to 'None' instead of an empty string.