Merging first draft of json export

[HLWeil]

#63

First functionality for getting arc subparts as json are included and can be exported via

arc export exports full arc as investigation.json
arc assay export exports all assays as studyList.json (to include persons)
arc assay export -n AssayName exports specific assay as study.json (to include persons)

For these commands also a -ps flag exists to retrieve everything as a processSequence.json (which is planned to be used as the major exchange format for interrogating the arc for experimental specifics)

For these commands also a -p argument exists to write the resulting json to a filepath