Initial Dockerfile for OMERO

This dockerfile is used to build all of OMERO in
a repeatable way. In order to reduce the amount of
context that must be copied into docker, only the
output of the `release-src` command (openmicroscopy*zip)
is passed for building.

The image once built can be used for working with OMERO
but it does not start a server itself. Use one of the
omedocker images for starting a full stack.