3.0 Beta 1

This release bring a ton of features. Because of that, some API and JSON schema changes were necessary.
Have a look at #295 for more details regarding what has changed.

Note, that this version is not backwards compatible. The JSON file produced by nRF Mesh 3.0 or the underlying library is not compatible with one accepted by nRF Mesh 2.x (including Android version). The nRF Mesh for Android will also be migrated to support the new schema in coming months.

To make that more clear, this is initially released as 3.0-beta1 and will be promoted to 3.0 when Android version is ready.