Refs #7830 - Change name to initial.
Refs #7830 - Allow consecutive DOIs to be linked together.

* Use IsNewVersionOf and IsPreviousVersionOf identifiers.
* Update the metadata of previous DOI's if they exist.
* Changes to when and how the script talks to Git.
* Refactor the http requests.
Merge branch 'feature/7830_doi_messages_on_startup' of github.com:mantidproject/mantid into feature/7830_doi_messages_on_startup