Added SharedPreferences to store the realms

This GlobalSettings will store all the info about the saved
realms.

Author: kunall17

app/src/main/java/com/zulip/android/ZulipApp.java

@@ -49,6 +49,16 @@ public class ZulipApp extends Application {
     private Set<String> mutedTopics;
     private static final String MUTED_TOPIC_KEY = "mutedTopics";
 
+    private final static String GLOBAL_SETTINGS = "HumbugActivity";
+    private final static String SERVER_SETTINGS = "serverSettings";
+    private final static String GLOBAL_SETTINGS_CURRENT = "currentRealm";
+    private static final String GLOBAL_SETTINGS_REALMS = "REALMS";
+
+
+    public int currentRealm = 0;
+
+    public HashSet serverStringSet;
+    private SharedPreferences globalSettings;
     /**
      * Handler to manage batching of unread messages
      */
@@ -86,13 +96,10 @@ public void onCreate() {
 
         // This used to be from HumbugActivity.getPreferences, so we keep that
         // file name.
-        this.settings = getSharedPreferences("HumbugActivity",
-                Context.MODE_PRIVATE);
+        globalSettings = getSharedPreferences(GLOBAL_SETTINGS, Context.MODE_PRIVATE);
+        currentRealm = globalSettings.getInt(GLOBAL_SETTINGS_CURRENT, currentRealm);
+        serverStringSet = new HashSet<String>(globalSettings.getStringSet(GLOBAL_SETTINGS_REALMS, new HashSet<String>()));
 
-        max_message_id = settings.getInt("max_message_id", -1);
-        eventQueueId = settings.getString("eventQueueId", null);
-        lastEventId = settings.getInt("lastEventId", -1);
-        pointer = settings.getInt("pointer", -1);
 
         if (BuildHelper.shouldLogToCrashlytics()) {
             // TODO(lfaraone): figure out what to do about crash reporting