Disable image attachments for remote contacts alpha.

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -239,7 +239,7 @@ public class AppModule {
 
 			@Override
 			public boolean shouldEnableImageAttachments() {
-				return IS_DEBUG_BUILD;
+				return false;
 			}
 
 			@Override

briar-api/src/main/java/org/briarproject/briar/api/messaging/MessagingManager.java

@@ -30,7 +30,7 @@ public interface MessagingManager extends ConversationClient {
 	/**
 	 * The current minor version of the messaging client.
 	 */
-	int MINOR_VERSION = 1;
+	int MINOR_VERSION = 2;
 
 	/**
 	 * Stores a local private message.

briar-core/src/main/java/org/briarproject/briar/messaging/MessagingModule.java

@@ -65,7 +65,7 @@ public class MessagingModule {
 		conversationManager.registerConversationClient(messagingManager);
 		// Advertise the current or previous minor version depending on the
 		// feature flag
-		int minorVersion = featureFlags.shouldEnableImageAttachments() ? 1 : 0;
+		int minorVersion = featureFlags.shouldEnableImageAttachments() ? 2 : 0;
 		clientVersioningManager.registerClient(CLIENT_ID, MAJOR_VERSION,
 				minorVersion, messagingManager);
 		return messagingManager;