default NODE_ENV to production
default NODE_ENV to production

Change-Id: Ice325e3f759ec126edc4ea12260a0d4f904a8f53
Reviewed-on: https://gerrit.instructure.com/69322
Reviewed-by: Corban Raun <493d004d1694a8662e0fba37160e3ca76fb512f9@instructure.com>
Product-Review: Mark Severson <cdf1f90aee9d0d073a2a24141ebc71887f3ba533@instructure.com>
QA-Review: Mark Severson <cdf1f90aee9d0d073a2a24141ebc71887f3ba533@instructure.com>
Tested-by: Mark Severson <cdf1f90aee9d0d073a2a24141ebc71887f3ba533@instructure.com>

instructure/dockerfiles,instructure/dockerfiles,instructure/dockerfiles,instructure/dockerfiles