v1.14.4 - Enforced usage of AID if available

Logic is as follows:
- Always check to see if AID is available, regardless of whether it is new/old user.
- If available, use AID.
- If not, use UUID.

NB it is possible for users to switch between IDs if the availability of the AID changes. This could lead to some users being counted twice. However this is a necessary evil to comply with the latest Android rules regarding the use of the advertising ID.