Make NetworkManagementServiceTest pass again.

1. Mock the service manager so that NMS can fetch mock versions
   of INetd and IBatteryStats.
2. Call LocalServices.removeServiceForTest to avoid a duplicate
   service registration error. // check this
3. Change the timeout from 100ms to 200ms, as otherwise the tests
   that check for IfaceClass fail.
4. Convert NetworkManagementServiceTest to JUnit 4.
5. Move NetworkManagementServiceTest to tests/net

Bug: 29337859
Bug: 32163131
Bug: 32561414
Bug: 62918393
Test: runtest frameworks-net
Change-Id: Ic7371b427b35809ccd446addf35c9d8ae99ccfd3