Get rid of the drop-down menu for input format selection

[armish]

Since it is pretty trivial to decide whether a sequence is in peptide or FASTA format with some validation rules either on the front- or back-end (similar concept: credit card forms and their automatic decision on the type of the card as the number is entered).

Here is an example implementation of such functionality: http://evfold.org/evfold-web/newmarkec.do. See the Enter Protein Sequence field which allows different types of input with no additional setup expectation from the user.

Could be implemented on the front- or back-end.