[split] Specify Content-Language: English

Google Chrome believes the admin panel is in Albanian, and kindly suggests
a translation. No thank you.

Signed-off-by: Jeff Smick <jeff@twitter.com>

RB_ID=151881
[split] small updates to twitter-server docs

RB_ID=151877
NO-QUEUE=true
[split] remove local resolver for twitter-server

RB_ID=152052
NO-QUEUE=true
Merge splits