Create the packs/ directory on install if the selected stickerpicker

repo didn't have it already

stpkg

@@ -357,6 +357,7 @@ EOF
         || die "Failed to git clone the stickerpicker project. Your config file ($STPKG_CONF_FILE) is probably corrupted, you should clean it by hand"
 
     cd $STPKG_INSTALL/   || die "Failed to cd to '$STPKG_INSTALL/'"
+    mkdir -p packs       || die "Failed to create 'packs' directory"
     cp packs/* web/packs || die "Failed to copy default packs to '$STPKG_INSTALL/web/packs/'"
 
     default_index > $STPKG_INSTALL/web/packs/index.json || die "Failed to create default index.json file"