[Super-Issue] Further implementation of Hilbert configuration parser and server/client-side CLI tools

[porst17]

This super-issue is about further implementing/extending parts of Configuration Design, remaining after merging PR (#34):

• Fix x11vnc BG service (6c6abf8)
• Configuration Validator: validation of unknown fields (Configuration Validator: validation of unknown fields #36)
• Configuration Validator: complex general validation (Configuration Validator: complex general validation #37)
• Make use of Travis CI (Add entry point for automated testing #1)
• Add Travis CI Badge to the README page.
• Fix generation of OGL.tgz for OpenGL usage from within docker containers
• cleanup directory structure / legacy files (3ecb4c4)
• improve client-side CLI (?).
• choose Python 2 or Python 3 for the server-side tool (Drop support for Python 2.x in favor of Python 3 #76)
• implement the computation of the set of stations within a Group (Configuration design: Reflect n:m relation between stations and applications in the configuration #15)
• Management Image should mount the Station SSH Access DB. See: (Configuration design: Separate Access Management? #25)
• implement the handling/checking of Profile::supported_types (How does hilbert know from the config which ServiceRuntime to use? #32)
• External hosting of configuration data, software and whatnot (External hosting of configuration data, software and whatnot #29)
• consider switching from argparse to some argument parser with sub-commands, e.g. http://click.pocoo.org/5/, https://github.com/docopt/docopt.
• Design configuration presets (Configuration Design: configuration preset #30)

Add more unit-tests as /tests/test_*.py, e.g. using pytest (Note: data files may be in /tests/data/):

• validation of unknown fields: (Configuration Validator: validation of unknown fields #36)
• DockerComposeService & DockerComposeApplication: (Configuration design: Service definition #19)
• Group (inherit from BaseRecordValidator) (Configuration design: Reflect n:m relation between stations and applications in the configuration #15)
• Profile::supported_types (How does hilbert know from the config which ServiceRuntime to use? #32)

Note: unfinished parts of older super-issue hilbert/hilbert-docker-images#28 are to be merged into this one.

[porst17]

To be worked on later:

• Support of configurable aliases for subcommands and external scripts (Support of aliases for subcommands and external scripts #33)
• Configuration Validator: modularity (e.g. validation with a json schema) (Configuration Validator: modularity #35)
• finish missing checks in Validators (finish missing checks in Validators #78)
• forward logging options from server tool to remote driver (forward logging options from server tool to remote driver #77)