Implement CrashReporter using libcrashreporter-qt

I consider this done. If you have any other wishes, please let me know.






- [x] add config option
- [x] hide config option if built without crash reporter
- [x] add build switch 
- [x] make the upload url configurable
- [x] brand crash reporter binary name
- [x] brand crash reporter text
- [x] brand crash reporter icon
- [x] add to installers
  - [x] Windows
  - [x] OS X