common: Fix bug of minimal ACL handling

This commit fixes issue that were found during some tests:
Some tests found an issue that 'getxattr()' handling returns a minimal xattr
ACL when there's a minimal ACL or no ACL at all. It should return a ENODATA
error instead. This commit fixes this behaviour.

Change-Id: I21816193b32ef78f5687387a7926ea1f894675d1
master: Add support for default ACL entries

This commit extends an ACL support in master server to cope with default
entries. There's no optimisations implemented (especially deduplication). To
support ACLs properly, when 'setxattr()' syscall with empty ACL is called (it
happens e.g. when copying directories with permissions preservation for default
ACLs), we remove an existing one.
'test_acl_behavior' is fully enabled, extended by links and fixed because some
too restrictive permissions caused always a failure.

Change-Id: Iefd20d3daf321079ba1d109d960be34714b62b6f