Enhance portal check code to return connectivity_state

doc/service-api.txt

Index: doc/service-api.txt
diff --git a/doc/service-api.txt b/doc/service-api.txt
index d92c0b86fc114d2adc9cfeb2ca554e8593eb186e..8919b645b12c4f41cad5caf9d19da53c09672837 100644
--- a/doc/service-api.txt
+++ b/doc/service-api.txt
@@ -286,7 +286,32 @@ Properties	string State [readonly]
 			certificate authority file for use in validating
 			server certificate recieved from the access point
 			during the 802.1x authentication process.
-			
+
+		string ConnectivityState [readonly]
+			This property indicates whether the data
+			connection is within a "walled garden", in
+			which only a restricted set of IP addresses
+			can be reached. A value of "restricted"
+			indicates that the connection is in such a
+			restricted IP pool.  A value of "unrestricted"
+			indicates that the connection has unrestricted
+			access to the internet, and a value of "none"
+			means that it is unlikely that any internet
+			access is available, despite having obtained
+			an IP address.
+
+			This property is only valid when the service
+			is the default service and is in the "ready"
+			state.  The default value is "unknown",
+			changing to "restricted", "unrestricted" or
+			"none" after enough time (~5 seconds after
+			becoming the default service) has elapsed to
+			establish the state of IP connectivity.
+
+			This state is currently only computed for
+			services of type Cellular, but it can be made
+			applicable to other services types.
+
 		boolean PassphraseRequired [readonly]
 
 			If the service type is "wifi", then this property
@@ -416,21 +441,6 @@ Properties	string State [readonly]
 			network. Possible values are "home", "roaming", and
 			"unknown".
 
-		boolean Cellular.RestrictedPool [readonly]
-			If the service type is "cellular", then this property
-			indicates whether the mobile data connection is within
-			a "walled garden", in which only a restricted set of
-			IP addresses can be reached. A value of "true" indicates
-			that the connection is in a restricted IP
-			pool.
-
-			This property is only valid when the service
-			is in the "ready" state.  The default value is
-			"false", only changing to "true" after enough
-			time (~5 seconds after becoming the default
-			service) has elapsed to assume that the IP
-			connectivity is restricted.
-
 		string Cellular.OlpUrl [readonly]
 
 			If the service type is "cellular", then this property