Fixup dockerfile, requirements, upgrade android gradle.

I'll merge this stuff in tracking for now, as there's some other stuff I'm working on and want these latest changes in.

pycar/src/car/tracking/algorithms.py

@@ -221,6 +221,8 @@ def assign_groups_II(prev_groups, new_groups):
         # TODO: Check the centres are within a certain threshold.
         new_groups[i].number = prev_groups[0].number
 
+    # TODO: Go through to put all groups into one (if multiple groups get same number) to avoid splits.
+
     return new_groups