Adding a CallService & CallServiceProvider concrete classes.

First step in no longer using ICallService and ICallServiceProviders
directly.
Adds a generic ServiceBinder class to manage binding/unbinding.

Change-Id: I7d26958dd85a99316dbd5e70caba3fd91d35911b
diff --git a/src/com/android/telecomm/CallServiceAdapter.java b/src/com/android/telecomm/CallServiceAdapter.java
index bfbdebd..ccfb2cc 100644
--- a/src/com/android/telecomm/CallServiceAdapter.java
+++ b/src/com/android/telecomm/CallServiceAdapter.java
@@ -31,6 +31,7 @@
  * check that the invocation is expected from that call service.
  * TODO(santoscordon): Move away from Runnable objects and into messages so that we create fewer
  * objects per IPC method call.
+ * TODO(santoscordon): Do we need Binder.clear/restoreCallingIdentity() in the service methods?
  */
 public final class CallServiceAdapter extends ICallServiceAdapter.Stub {