Add pipeline-utility-steps for readJSON

Add test based on https://github.com/mkobit/jenkins-pipeline-shared-libraries-gradle-plugin. Currently times-out after sending and receiving HTTP req/res.

Ensure data inserted into jobDraft

Delete by path not label

Delete jobDraft only if present

Debugging issue with uploadTidy() not appearing to be called when optional datasetPath argument isn't supplied.

uploadTidy takes optional datasetPath argument ...

Also requires that we delete datasets by path, not label

Improved jobDraft logging

jobDraft.replace Try with finally

Split draft creation and use ...

Requires drafts to be created in the job, not per operation

drafter.findOrCreateDraftset

Skip deleting draftset

Skip filename in self-call

Oh my typo

See if coercion helps groovy find drafter.findDataset ...

java.lang.NoSuchMethodError: No such DSL method 'findDraftset' found among ... globals [..., drafter, ... ]
    ...
    at dataset.delete(/var/jenkins_home/jobs/GSS_data/jobs/Migration/jobs/ONS-Local-Area-Migration-Indicators/builds/44/libs/pmd/vars/dataset.groovy:10)

More findDraftset typos

s/draftset/drafts typo

Extract dataset.delete and draftset.findDraftset

Extract util.slugise()

Output some debug info.

Explicitly check not-null oldLabel. Lowercase old label.

Add type in case it matters.

Add optional 'oldLabel' argument to help ensure previous graphs are removed.

Remove extraneous bracket.

uploadTidy to replace uploadDraftset; use empty dataset label so title isn't overridden in metadata.

ons-table2qb.core/data-cube uses new parameter, 'dataset-slug'

Put columns mapping CSV file in metadata directory so it doesn't interfere with other CSV files.

Use brackets.

Attempt to use updated data-cube pipeline with additional columns-csv parameter.

Add method to upload data cube observations and metadata as turtle/trig respectively.