Add reporting of previous oncotree codes

The Web API's and the main website now display a list of any previous oncotree codes which represent the same class of tumor types as any returned oncotree code.

In the Web API, the model for tumorType contains an element named "history" which was a list of objects. Now the "history" element returns a list of Strings which contain any previous oncotree codes used for the same conceptual tumor types. (previous to the release queried)

In the website, if any previous oncotree codes exist for a node in the tree, then when the user hovers over the node, they will be displayed in the popup box. (labeled "previous codes:")

Oncotree representation now in TopBraid Repository

Instead of a table-based representation of the oncotree, an external TopBraid system provides a proper graph database storage engine and API for representing the OncoTree nodes nodes, relationships, and meta data (such as color, and mainType).

OncoTree versioning is enabled through a separate TopBraid Taxonomy storing all available versions with descriptions and needed identifiers for API and repository access.

Unit testing introduced, focussing on the services / utilities needed for the API.

Some small improvements to the frontend, such as a dropdown selector showing a list of available versions.

Also, partial code cleanup of unused features and api output fields. Updates to spring library components (newer versions).

One tumor type has been added under Bowel

Medullary Carcinoma of the Colon (CMC) has been added under Bowel

Official first release of OncoTree data

The first release of OncoTree tumor types list. Now we have 507 tumor types from 32 tissues.