Improve acceptance tests.

- split registration API and regular registration
Remove acceptance test about hash tags (if we need that, we'll have another story for it)
Merge pull request #84 from miphe/dro/create-entry-tweak

Remove acceptance test about hash tags
Merge pull request #83 from miphe/dro/registration-docs

Improve acceptance tests.
Clarify readme, accessibility for contributors

- Clarify high level usage
- Make "How to contribute" section more verbose.

etc.