GSM library to the new format and some strings adaptations

libraries/GSM/arch/avr/GSM3ShieldV1ModemVerification.cpp

@@ -69,7 +69,7 @@ String GSM3ShieldV1ModemVerification::getIMEI()
 	modemResponse.toCharArray(res_to_compare, modemResponse.length());
 	if(strstr(res_to_compare,"OK") == NULL)
 	{	
-		return NULL;
+		return String(NULL);
 	}
 	else
 	{

libraries/GSM/arch/avr/GSM3ShieldV1ScanNetworks.cpp

@@ -63,7 +63,7 @@ String GSM3ShieldV1ScanNetworks::getCurrentCarrier()
 		String final_result = ptr_token;
 		return final_result;
 	}else{
-		return NULL;
+		return String(NULL);
 	}
 }
 
@@ -82,7 +82,7 @@ String GSM3ShieldV1ScanNetworks::getSignalStrength()
 		final_result.trim();
 		return final_result;
 	}else{
-		return NULL;
+		return String(NULL);
 	}
 }
 

libraries/GSM/library.properties

@@ -0,0 +1,10 @@
+name=GSM
+author=Arduino, Telefonica+ID
+email=info@arduino.cc
+sentence=With this library you can use the Arduino GSM shield to connect on GSM and GPRS networks
+paragraph=Use this library to make/receive voice calls, to send and receive SMS with the Quectel M10 GSM module.</br>This library also allows you to connect to internet through the GPRS networks. You can either use web Clients and Servers.</br>
+url=http://arduino.cc/en/Reference/GSM
+architectures=avr
+version=1.0
+dependencies= Software Serial
+core-dependencies=arduino (>=1.5.0)