Remove validation of type in fails for upload

[Doc94]

This close #4280 by removing the validation of file type.

Based in a note about File.type this property only work for a few files like normal text or images, for the rest of files (like .db, .jar) this return empty then its a valid form to check a file in the upload process.

i dont know fully the system for try to suggest a better form for validation but can suggest this little fix.