Updated mediawiki/extensions
Project: mediawiki/extensions/GettingStarted  bbaddea4daed3bd4c52878456077255113d346e4

Use GettingStarted namespace for all classes

This will also facilitate refactoring for bug 55598 and bug 55773,
since name collisions with unrelated code will not be a possibility.

Change-Id: I4f096ad66547bac9c914ff0df4d8dd6dfe86a4c3