No-op cleanup of ConnectivityService.

Funny how these things accumulate. Not exhaustive of course, but
still an improvement.
- Remove unused imports.
- Remove unused variables and members.
- Replace members with locals where applicable.
- Remove useless type parameters and explicit unboxings for Java 7.
- Conversely add the diamond operator for auto-genericity for
  Java 6.
- Reduce visibility of members where possible.

Test: runtest frameworks-net
Change-Id: I13586aee09b4cd1c87c525fafb5eee44dedb5360