[dev-util] Add stage_debug,symbolicate_dump endpoints to dev server

Add an endpoint to the dev server that will synchronously download
and stage the debug symbols for a given build.
Add an endpoint to the dev server that will symbolicate a minidump.

BUG=chromium-os:29850,chromium-os:30399
TEST=unit
TEST=run dev server, use curl to make it download some artifacts; ensure
TEST=debug.tgz is _not_ downloaded immediately, but that the rest of the build is staged.

TEST=run dev server, use curl to make it download debug_symbols; check to
TEST=see that debug symbols are staged in static/archive
TEST=once symbols are staged, run the dev server in your
TEST=chroot and use curl with a minidump file like this:
TEST=  curl -F minidump=@/home/cmasone/chromeos/phooey/powerd.20120424.141235.1005.dmp http://localhost:8080/symbolicate_dump

Change-Id: Ie460526396d2b9999137142c723b87793bc23aaa
Reviewed-on: https://gerrit.chromium.org/gerrit/21696
Reviewed-by: Chris Sosa <sosa@chromium.org>
Commit-Ready: Chris Masone <cmasone@chromium.org>
Tested-by: Chris Masone <cmasone@chromium.org>
6 files changed