Update Xabber Classic to 0.9.31 (105)

Also:
* Really enable Xabber Classic
* set AUM

metadata/com.xabber.android.classic.txt

@@ -1,4 +1,3 @@
-Disabled:Wait for https://gitlab.com/fdroid/fdroidclient/issues/313
 Categories:Internet
 License:GPLv3
 Web Site:http://www.xabber.com
@@ -49,7 +48,16 @@ Build:0.9.30g,103
     prebuild=sed -i -e '/otr4j.jar/d' build.gradle && \
         cp -fR $$Otr4j$$/src/net src/main/java
 
-Auto Update Mode:None
+Build:0.9.31,105
+    commit=0.9.31
+    subdir=app
+    gradle=yes
+    srclibs=Otr4j@7fb42b2ef912fe664064edf717a6b72ce77ccb3b
+    rm=app/libs/*.jar
+    prebuild=sed -i -e '/otr4j.jar/d' build.gradle && \
+        cp -fR $$Otr4j$$/src/net src/main/java
+
+Auto Update Mode:Version %v
 Update Check Mode:Tags ^0\.9.*$
 Current Version:0.9.31
 Current Version Code:105