[Qt] update bitcoin-qt.pro and assets-attribution.md

- remove unused and unmentioned file notsynced.png (we use an animation
  for this)
- add missing coincontroldialog.ui to bitcoin-qt.pro
- also unify formating in assets-attribution.md
Merge pull request #3432

b960fcb [Qt] update bitcoin-qt.pro and assets-attribution.md (Philip Kaufmann)