Fix formating of log statment that failed presubmit check.

BUG=skia:
TBR=jcgregorio

Review URL: https://codereview.chromium.org/787133002
Add run_lua worker script and add more utils

The run_lua worker script reads in SKPs generated from Alexa's top 1M CSV and
runs the specified lua scrapping script on them. The results of the run are then
uploaded to Google Storage.

Also made the following improvements:
* Added ability to output stdout and stderr to glog and optionally to a file in util.ExecuteCmd
* Added utils for syncing dirs and building Skia tools in util.go
* Added UploadFile method in gs.go for uploading specific files.

BUG=skia:3163

Review URL: https://codereview.chromium.org/790793002