Multiple updates to 'Create term' window

[jamesrwelch]

When creating a new term, the following window appears:

The following changes are required:

• The window should be larger by default
• The 'description' field should be an html editor
• The 'definition' field should be optional - if no definition is supplied then the API call should set the definition to be the same as the code.
• After creating the term, the UI returns to the terminology page - this should follow the same pattern as other 'create' methods and send you to the description tab of the newly-created term.

[jamesrwelch]

(Sorry for multiple issues in one ticket, but they can probably all be addressed at the same time)