Remove more invalid chars

app/src/main/java/chat/rocket/android/helper/ServerPolicyHelper.java

@@ -16,7 +16,8 @@ public class ServerPolicyHelper {
       return "demo.rocket.chat";
     }
 
-    return removeTrailingSlash(removeProtocol(enforceDefaultHost(hostname)));
+    return removeExtraInvalidChars(
+        removeTrailingSlash(removeProtocol(enforceDefaultHost(hostname))));
   }
 
   public static Observable<ServerValidation> isApiVersionValid(
@@ -50,6 +51,10 @@ public class ServerPolicyHelper {
     return hostname.replaceAll("/+$", "");
   }
 
+  private static String removeExtraInvalidChars(String hostname) {
+    return hostname.replaceAll("[^\\w|\\.|\\-|/]", "");
+  }
+
   private static boolean isValid(JSONObject jsonObject) {
     if (jsonObject == null) {
       return false;