Add support for optional properties

In the "Add Property" dialog, there is a new section 'Template Properties'
that will work together with the template extension. Instead of just
properties that are in use elsewhere, properties that are listed in the
template are displayed here.
Labels for 'Add Property' dialog.

Labels for the 'Add Property' popover window will be parsed correctly and
will also accept labels from the template extension.
Add functions to meta widget
Adjust the way the RDFauthor reset

After values have been commited and all edit proccesses are terminated,
the RDFauthor will only do a 'gentle' reset. In conjunction with the
disabled reloading, this will allow to edit values more quickly. This is an
ongoing endeavour and previously, there have been some glitches (e.g. submit
on enter did not work correctly) which are (hopefully) fixed now.
Add an experimental spinner/ajax loader screen

When creating a new resource, it is sometimes not obvious that OW does a
reload. This commit adds a spinner after committing the new resource.
Correct handling of widgets in inline editing

There was an error when using the meta widget (where one can choose
between literal or resource).

This commit also introduces the possiblity to reload after changes to
the type (only in commented code). This needs some further evaluation.
Add more i18n for literal and resoure widgets
Disable input field when committing

Input and text fields will be disabled and 'grayed out' while being
submitted.
Merge branch 'feature/rdfauthor-FormBuilder' into deployment/erm-hd

Conflicts:
	src/rdfauthor.popovercontroller.js