godoc: allow form feed in text files
godoc: allow form feed in text files

Now recognizes misc/emacs/go-mode-load.el as text.

Fixes issue 2115.

R=gri
CC=golang-dev
http://codereview.appspot.com/4801061

dsriram/golang,pombredanne/go-deleteme,dsriram/golang,pombredanne/go-deleteme,apparentlymart/golang,tv42/old-go,dsriram/golang,tv42/old-go,apparentlymart/golang,pombredanne/go-deleteme,apparentlymart/golang,gnanderson/go,gnanderson/go,apparentlymart/golang,dsriram/golang,gnanderson/go,tv42/old-go,pombredanne/go-deleteme,gnanderson/go,apparentlymart/golang,pombredanne/go-deleteme,gnanderson/go,tv42/old-go,tv42/old-go,gnanderson/go,apparentlymart/golang,tv42/old-go,pombredanne/go-deleteme,gnanderson/go,pombredanne/go-deleteme,dsriram/golang,dsriram/golang,tv42/old-go,dsriram/golang,apparentlymart/golang