No way to add a file for a few parameters of the Call Variants worker

1. Open the Call Variants Pipeline from the samples
2. Try to specify parameters (using wizard or wd standard interface) with files (like BED or position file list, List of sites, etc.)
Expected state: the files can be selected.
Bug state: it asks to specify a folder

Additional:
-Check that each changed parameter works as in original SAMTools (http://samtools.sourceforge.net/)
-Provide an automatic test for each parameter