Add initial service-less implementation.

This commit cleans up minor differences and adds
a code path for executing "admin start" without
creating a service on Windows. The Command Prompt
will be locked.
Remove print command.
Fix flake8 errors.
Use whitespace-safe command on *nix.
Remove JDK 5 syntax from templates.xml.
Ongoing work on CLI params.
Use -fg instead of -s.
Implement foregrounding for Unix and Windows.
Make sure server suspends in debug mode.
Use two hyphens for "fg" argument.
Fix bin/omero admin start.
Merge pull request #2789 from bpindelski/12281_debug

Allow foregrounding of the server process (see #12281).