(FR #1771) Skip lines before the headers in malformed CSV files

Change-Id: I23b9bf5d6786706e8f84d8c16d80fe8f497644b7
(FR #1771) Some UI cush to make uploading more pleasant

* Prevent form submit until a file is selected
* Try to autodetect file format from the name

Change-Id: Ic8c410f0b709bffac311ab3835e222641d0e3987