classes/sstate: fix file conflict message

classes/sstate: fix file conflict message

* Fix not decoding output from grep ("Matched in b'manifest...')
* Fix showing "Matched in b''" if no match (show "not matched to any
  task" instead)
* Drop the filtering out of .populate-sysroot from matched manifest
  names - it should have been .populate_sysroot so it doesn't work, and
  in any case the value of removing the task name is questionable given
  that we aren't removing it for any other task, and that the rest of
  the filename isn't only the task name, we might as well have the whole
  thing. At least then you can do a find on that exact name without
  wildcards and find it.
* Fix indenting of file list entries and indent "matched in" further
  underneath
* Minor punctuation fixes

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>