Allow for changing project tracking default to false

[verymilan]

Hi there, because I just tapped into this requirement with somebodies deployment, I'd like to create this as a feature request because every related ticket/pull seems to be closed. The organization in question does not want to include tracking. While yes, it can be turned off per campaign, they are now afraid of potential user error.

• Allow tracking to be disabled #151 was mentioning this but got closed prematurely
  • related merged pull Add do-not-track option for campaigns #152 mentions that this needs defaults implemented in general

Perhaps Keila could look for a environment variable until this is implemented?