uninstall before reinstall of omemo plugin

src/freedombone-app-xmpp

     set_repo_commit $INSTALL_DIR/profanity-omemo-plugin "profanity omemo plugin commit" "$PROFANITY_OMEMO_PLUGIN_COMMIT" $PROFANITY_OMEMO_PLUGIN_REPO
     cd $INSTALL_DIR/profanity-omemo-plugin
     sed -i 's|python setup.py|python2.7 setup.py|g' $INSTALL_DIR/profanity-omemo-plugin/install.sh
+    pip uninstall profanity-omemo-plugin
     ./install.sh
     for d in /home/*/ ; do
         USERNAME=$(echo "$d" | awk -F '/' '{print $3}')