First release with MIAPPE compliant ISA-Tab files

This version includes:

• Major rewrite in the assay, study, investigation, data and trait file generation towards MIAPPE compliance
• improved performance and stability
• improved endpoint handling
• Working docker
• JSON export
• included ISA validator
• assay and data files generated based on observation level
• Better handling of missing attributes
• Almost all mandatory MIAPPE fields are implemented

NOTE: MIAPPE fields that are not included in BrAPI are filled in with 'NA in Brapi' and need to be filled in manually using a text editor.