Taxon concepts page functionality

In this branch:

- Species+'s taxon concept page is improved, with information being split across the different tabs;
- Interaction with lists of information is added for the Legal tab and for common names in the Names tab;
- Sprites for Appendices and Annexes are added into the project and used in the Legal tab;

The pull request is created to deploy this version of the site ahead of our meeting with CITES.

Work still needs to be done:
- Add messages for when data is not available;
- Fix issue with redirecting to the legal tab when using any of the other links;
- Collapse/expand behaviour for references' tab