Add a SKIP_STATIC_UPLOAD env variable check (that won’t upload anything to S3). 

/cc @kmanning
Whoops, need some async task `done()` calls when breaking early.
Merge branch 'master' into runtime-deps

* master:
  Whoops, need some async task `done()` calls when breaking early.
  Add a SKIP_STATIC_UPLOAD env variable check (that won’t upload anything to S3).

Conflicts:
	package.json