Fix add_fw to allow multiple submissions. 

Fix add_fw to allow multiple submissions. Seriously, there is no need for the add_wf_dir. 
You just need to do "lpad add_fw 1.yaml 2.yaml" or "lpad add_fw *.yaml" or "lpad add_fw dir_name/*.yaml" (if your yamls are in a subdir) and everything will work fine. This is in fact a far more flexible syntax that works like you expect from most command line applications.