dashboard: increase notification log to 200 lines
dashboard: increase notification log to 200 lines

The go command lists all packages that were built.
A recent breakage notification included this text:

$ tail -100 < log
ok      errors
ok      exp/ebnf
?       exp/ebnflint [no test files]
ok      exp/gotype
ok      exp/norm
ok      exp/spdy

If the breakage occurred before this point it would
not be visible in the output.

R=golang-dev, gri, kevlar
CC=golang-dev
http://codereview.appspot.com/5504109

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