GA improvements

[davidread]

Improve Google Analytics stats, based on the performance we want to track.

Based on

• User needs performance benchmarks
  • https://docs.google.com/document/d/1DOC4xMLfFz6qKYwbxqcJ5BmAHz3pacSlXByIhnGUikw/edit
• Regular performance stats
  • https://docs.google.com/document/d/1GyxP8vDP3XErI78Rl5M_pdVEWq3TWNHztHLvPR5hRN0/edit

Looking into custom dimensions
https://docs.google.com/spreadsheets/d/1MjFUGp479CF_9_CtmBCBy4FXmTsjeOT28oXgX9dKgbU/edit#gid=0