Moves category defintions from DataSet to DataSetManagementObject and adds prep functionality to add/edit/view categories. Default category is "Other".
Breaks search indexing for categories, this will be fixed in issue #81 (closed)
- Add a dataset, the radio-button-like control to choose the main category should appear (the main category defines, which curators are in charge of the dataset)
- Edit the dataset and another control (select like) to choose additional datasets (only used for search) should appear
- Both control should work as expected