git: Give reasonable default size to git dock
launcher: Don't say successfully - just show the error code (bgo#726607)
Miscellaneous improvements to the About dialog

* Reduce the width of the Credits page
* Use GtkLicense
* Use the correct copyright sign. (It can be omitted, but we shouldn't
  display (c) in our programs.)

https://bugzilla.gnome.org/show_bug.cgi?id=726606