Embedded schedule view

Allow the schedule to be embedded in external platforms.
Hide header and footer when embedded for easier consumption.

Update speaker styling

Use site base template for all pages.
Fix speaker profile to work with Bootstrap 4.

More dashboard and settings themes (#29)

* Proposals forms now have a header panel

* Adds panels to the speaker forms

* Imports latest pinax accounts templates

* speakers/base and proposals/base now derive from utility_page.html

* Most login forms now derive from take flight themes

* Missed email_confirm

* More accounts bits

* Restructures login form

* Puts submit etc buttons inside fieldset borders

Refactors all speaker-facing forms and editing pages to use the new theme (#27)

* Themes speaker_edit.html

* speaker_create now uses takeflight theme

* proposal_submit_kind now uses takeflight theme

* fixes bug in form_snippet

* Optimises proposals_submit_kind

* proposal_submit now uses wagtail theme

* Proposal_edit now uses new theme

* More forms

* Proposal details page now loads from take flight theme

* proposal_fields now looks nicer under the take flight theme

* proposal_speaker_manage rethemed