app: remove hg dashboard
app: remove hg dashboard

It's time.

Fixes golang/go#11152

Change-Id: I9211e2cac5e73870f613fbc13d825df426ee11e6
Reviewed-on: https://go-review.googlesource.com/10917
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

evandbrown/build,golang/build,golang/build,golang/build,proppy/build,proppy/build,evandbrown/build,proppy/build,evandbrown/build,golang/build,proppy/build