Replace "Actions" dropdowns with explicit "Add" and "Edit" buttons

* Removes "Actions" dropdown from speaker detail page and section page (fixes #246)
* Adds "Add section" and "Add speech" buttons to speaker detail page and section page
* Slightly modified layout for speaker header section, to accommodate "Edit speaker" button

I merged in the changes from branch [245-speech-detail](https://github.com/mysociety/sayit/compare/245-speech-detail) since it included the correct solution [Duncan was search for](https://github.com/mysociety/sayit/issues/221#issuecomment-43423736) to pass the `request` object into views and templates. Hope that's ok.

The tests pass, and I've checked it all looks ok when included in the sayit.mysociety.org project.