RFC: give overlays a title

[Fania Bremmer]

** Proposed Change **
If the user opens a window/overlay by touching a button, this window 
should show a title (for example the "add new activity" window)

** Reason For Change **
For example at the user testing I experienced that people tried to start 
apps in the Add-Resources-Dialog, because they thought its some sort of 
app launcher. I guess it would be better to consistenly give sensitive 
titles to overlays that had been openend by taping a button to guide the 
users more.

My suggestion for our current windows/overlays (how do you call them 
technically?):
- Add new activity
- Add content (instead of items or resources)
- Settings activity

** Implementation Details **
- add title