Render mathjax partial with context (#638)

Closes #233

Author: stefanv

layouts/_default/baseof.html

@@ -12,7 +12,7 @@
     {{ partial "css.html" . -}}
 
     <!-- Add MathJax, if needed -->
-    {{ partial "mathjax.html" }}
+    {{ partial "mathjax.html" . }}
 
     <!-- Render custom user header -->
     {{ partial "head.html" . -}}