Autodetect or automate number of features

[stefangary]

Currently, the SL workflow gets the number of features from the workflow.xml launch form. If a .csv with N columns is sent the workflow and the number of features is M, then it will assume that the N - M remaining columns are targets.

This is nice but could be tricky if you don't know exactly the number of features you'll be using at the very beginning of the workflow. A more intuitive approach would be to look for an explicit list of targets and rearrange the input files to accommodate the targets. Ideally, the form would be dynamic and could allow the user to select targets based on the column headers of the specified input file.