Add version in app

Refs #48 (closed)

This adds the version within the app in the About panel, using git describe --tags --always:

• Until we have a tag, it displays only the commit sha1:
  
• When deployed on a tag:
  
• When deployed ahead of a tag (e.g. <tag>-<number of commits ahead>-g<commit sha1>):
  

Note: I used the tag 24.1 here for the example, it should have been prefixed with v (i.e. v24.1).