Description of problem:
Modal dialog which is opened when adding panel to a page has no title. This gives UI inconsistent feel, with some modal dialog having a title and some not having one.

Version-Release number of selected component (if applicable):
6.0.0.DR3

How reproducible:
Always

Steps to Reproduce:
1. Build application from sources on github and start quickstart demo using buildandrun_h2.sh as described in readme.
2. Login with root
3. In the black management bar at the top click icon with label "Create a new panel in the current page"

Actual results:
Modal dialog appears, but it has no title.

Expected results:
To ensure GUI consistency, the dialog should have some user comprehensible title, like "Add panel to current page" or "Select panel to add".

Additional info:
Also titles of other modal dialogs popped up by the application should be revised. For example when editting panel using its Options > Edit Content, the title is "Panel Edition" (as far as I know "Edition" is a term used in book publishing, not for editing something) - it should be rather something like "Edit panel content"