Update dependencies to current Debian stretch versions

stretch.pip

@@ -1,11 +1,10 @@
-Flask==0.10.1
+Flask==0.12
 Jinja2==2.8
 MarkupSafe==0.23
-Werkzeug==0.10.4
+Werkzeug==0.11.15
 itsdangerous==0.24
-Babel==2.1.1
-Flask-Babel==0.9
-pytz==2012c
-speaklater==1.3
+Babel==2.3.4
+Flask-Babel==0.11.1
+pytz==2016.7
 Flask-WTF==0.12
-WTForms==2.0.2
+WTForms==2.1