Merge pull request #9 from rombert/master

Cleanups and trivial fixes
Fix #12: Unable to edit jcr:title property

The 'right' way to determine read-only properties is to look at the
property definition.

Of course, ACLs might not allow editing this property, but that's out of
scope for now.
System properties: align the layout to match the one from the custom
properties.
Merge pull request #13 from rombert/issues/12

Issues/12
Modified properties window