md5 still calculated by application when input by user

I came across this issue when I was trying to add a very large mod to the TechnicSolder mod library, it would timeout and not add the mod. I then calculated the md5 myself but when I put it into the input box and click 'Add version' the application still attempts to calculate the files md5.

[skwerlman]

related: #545 #479 #469

[nathan130200]

Same issue when i try add MCHeli mod (over 100MB file size)