testlog: initial python implementation of testlog json api

Since we would like a general logging format that both Goofy
and other factory software can use, we define a JSON API called
"testlog".  This is the base Python implementation (with only
support for one event type so far, "station.init").

Initially there will be no validation support.

BUG=chromium:609069
TEST=Manually on DUT

Change-Id: Ic1cf9693b599dcf27cbccd917a3f5c1b0b6c967e
Reviewed-on: https://chromium-review.googlesource.com/339826
Commit-Ready: Joel Kitching <kitching@chromium.org>
Tested-by: Joel Kitching <kitching@chromium.org>
Reviewed-by: Chun-ta Lin <itspeter@chromium.org>
2 files changed