Allow other kinds of configuration files

[marcverhagen]

Now the pipeline runs off of a docker-compose configuration file. Add simpler ways to do this, for example by having a file like this:

tokenizer 0.0.0.0:5001
spacy 0.0.0.0:5002

or

tokenizer clams_tokenizer:5000
spacy clams_spacy:5000

[marcverhagen]

Mostly obsolete because of issue #7. But we could allow as an alternative to that an option where the configuration is a set of image names.