Add more margin at top of inside gov graph.

The most recent annotation was being clipped at the top.

@gtrogers
@robyoung
Correct department acronym.
Fixing performance homepage style

- rendering on ie7 & ie8
- margins at low resolutions

@maxfliri
Fix link to GDS Perfromance Blog

@maxfliri
Disable JSON parser

Remove potential attack vector.
Upgrade to rails 3.2.12

Following the security advisory about rails and json, upgrade both.