Make incoming calls work.

This is a CL of random changes. Ties of loose ends which were previously
commented and adds new wiring to connect all the pieces together.

After this CL, incoming calls are functional for call services.

Change-Id: I6fa1e70b816094587849329790236f9289ec260b
diff --git a/src/com/android/telecomm/Call.java b/src/com/android/telecomm/Call.java
index 4576075..7049742 100644
--- a/src/com/android/telecomm/Call.java
+++ b/src/com/android/telecomm/Call.java
@@ -64,6 +64,13 @@
     private CallInfo mCallInfo;
 
     /**
+     * Creates an empty call object with a unique call ID.
+     */
+    Call() {
+        this(null, null);
+    }
+
+    /**
      * Persists the specified parameters and initializes the new instance.
      *
      * @param handle The handle to dial.