Improve taxonomy for categorising sites

- Copy latest form content from stage.blocked Modx
- Add more comprehensive taxonomy for sites

Close #22

/cc @JimKillock, @webal, @ruthc
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- Form option only - no back-end implementation yet.

Close openrightsgroup.org/cmp-issues#23
Fix whitespace
Fix typo; remove 'blank' content types
Merge pull request #60 from openrightsgroup/feature/form-changes

Form changes