setup: Add update_catalogs command

This will update all catalogs with the template.

po/update_all_po.sh

@@ -1,5 +0,0 @@
-#!/bin/sh
-# Update translation files
-for po_file in `ls *.po`; do
-  msgmerge -N -U ${po_file} terminator.pot
-done

setup.py

@@ -250,6 +250,7 @@ setup(name=APP_NAME,
       tests_require=test_deps,
       extras_require={'test': test_deps},
       package_data={'terminatorlib': ['preferences.glade', 'layoutlauncher.glade']},
-      cmdclass={'build': CustomBuild, 'install_data': InstallData, 'uninstall': Uninstall},
+      cmdclass={'build': CustomBuild, 'install_data': InstallData, 'uninstall': Uninstall,
+                'update_catalogs': UpdateCatalogs},
       distclass=TerminatorDist)