BISERVER-11010 - Administrator role does not show on Share tab for existing and new folders

What was done:
1) added field is modifiable to AceAcl DTO
2) changed ui to take care of the field
3) changed WS to ignore non-modifiable role and to add admin role for
display only
Merge pull request #1412 from kolinus/BISERVER-11010

BISERVER-11010 - Administrator role does not show on Share tab for exist...