Fix service mailman_meta

 - create new files also for empty mailinglists
 - slavescript can find differences between old state and new empty file
   state (even if all members are gone now)
REGISTRAR, CORE: fixed parsing common name

CORE

- Parse parts of common name only if matcher.find() returns true.
- This cause method to return map with "namePart"=null on no match
  instead of throwing an exception.

REGISTRAR

- Added checks to call parseCommonName() only on non-empty and != null input.
- Do not overwrite "displayName" to "Shib-Person-displayName" as attribute
  name to get from federation values.
REGISTRAR: better pre-fill of user's name

- When filling form item mapped to perun attribute displayName,
  if value is not provided by perun or federation (concrete attribute),
  try to recreate it from parsed name (which is best of displayName,
  cn or givenName+sn).

  So if value is provided by Perun, it's filled.
  If it's provided by federation and present, it's overwritten.
  If it's provided by federation and missing, try to get best
  of all provided attributes (if not set by Perun already).
Merge pull request #559 from zlamalp/displayName

REGISTRAR, CORE: fixed parsing common name
Merge pull request #508 from stavamichal/fixMailman_meta

Fix service mailman_meta
add perun-engine-new and perun-dispatcher-new to the build, fix typo