[FIX] doc: increase requirement

Partial cherry pick of e4b75149
Sphinx 1.6.7 is the minimum in debian stable and ubuntu LTS

doc/_extensions/odoo_ext/translator.py

@@ -60,6 +60,7 @@ class BootstrapTranslator(nodes.NodeVisitor, object):
         self.context = []
         self.section_level = 0
 
+        self.config = self.builder.config
         self.highlightlang = self.highlightlang_base = self.builder.config.highlight_language
         self.highlightopts = getattr(builder.config, 'highlight_options', {})
 

doc/requirements.txt

-sphinx>=1.2
+sphinx>=1.6.7
 sphinx-patchqueue>=1.0