Fixing #1359. We are not using itex mode in sympyprinting.

Previuosly we were using itex=True in the sympy latex printer.
I don't know why where were doing this but we should use regular
printing mode and put the $$ around the equations ourselves.

IPython/extensions/sympyprinting.py

@@ -58,9 +58,9 def print_png(o):
 
 def print_latex(o):
     """A function to generate the latex representation of sympy expressions."""
-    s = latex(o, mode='equation', itex=True)
+    s = latex(o, mode='plain')
     s = s.replace('\\dag','\\dagger')
-    return s
+    return '$$%s$$' % s
 
 
 _loaded = False