use + as build metadata delimiter

build.gradle

@@ -95,11 +95,11 @@ android {
     productFlavors {
         playstore {
             dimension "distribution"
-            versionNameSuffix "-p"
+            versionNameSuffix "+p"
         }
         free {
             dimension "distribution"
-            versionNameSuffix "-f"
+            versionNameSuffix "+f"
         }
         system {
             dimension "emoji"

src/main/java/eu/siacs/conversations/entities/MucOptions.java

@@ -2,7 +2,6 @@ package eu.siacs.conversations.entities;
 
 import android.annotation.SuppressLint;
 import android.support.annotation.NonNull;
-import android.util.Log;
 
 import java.util.ArrayList;
 import java.util.Collections;