create synse server docker image 'lite' tag for synse-server without emulator

[edaniszewski]

Description

Synse Server doesn't need the emulator shipped around with it. The image with Synse Server + emulator is useful for getting started / testing / development, etc. but if someone is using Synse Server in production, the emulator isn't needed there.

There should be either a 'lite' tag which is Synse Server sans emulator, or that should be the norm and there be an 'emulator' tag for the versions with the emulator built in.

[edaniszewski]

as I feared, it does not look like there is an easy way to pass different dockerignore files to docker build so this will likely require a somewhat hacky solution.