Add missing PDF extraction support

README.rst

@@ -24,10 +24,12 @@ Requirements
 Software
 --------
 
-- PostgreSQL (9.4 or greater)
-- Redis (2.6 or greater)
-- Python 3 (3.4 or greater)
+- PostgreSQL (9.5 or greater)
+- Redis (3.2 or greater)
+- Python 3 (3.5 or greater)
 - LibreOffice (5.0 or greater)
+- Poppler (poppler-glib 0.45 or greater)
+- Python 3 GOBject
 
 Hardware
 --------

vowel.yaml

@@ -17,6 +17,8 @@ image:
         pkglist:
           - python3-lxml
           - libreoffice-impress
+          - poppler-glib
+          - python3-gobject
     - copy:
         src: ../vowel
         dest: /srv/vowel