Working on tape type lookup

 - fleshed out cv.cvv_ttype_lookup, cv_lib.ttype_lookup
 - new cv_lib.ttype_cart_lookup -- retrieve type and subtype numbers for a
   specific cartridge
 - new cv_lib.ttype_map_desc -- convert type and subtype number into a string
   media description
 - new util.lsp_parse -- take the output from an hsi 'ls -P' command and
   extract 1) the item type ('f' or 'd'), 2) the item name, 3) the cartridge
   if any, and 4) the cos if any. These are returned as a tuple.

Change-Id: I3b354263246d663ea27b239c653f67e6bef00848