Moved participant app to eluminate_web/apps/.
Added new table Category (with one item 'Other') and foreign key to it
from Participant.
Created virtual exhibition landing page.
Logos in Participant selector now click through into Participant detail
screens, which also contain category filter and Participant selector.
Moved markup for category filter into the participant selector template
and deleted the filter template.
Provide a context_object_name for ParticipantDetailView to avoid
confusion between current participant and the participant within
iterations through participant_list in selector.
Added an extra layer of template inheritance - participant_base defines
the participant selector and filter for top of participant screen,
extending templates participant_landing and participant_detail provide
inner content.
Include underscores and hyphens in slug pattern in participator detail
url.
Improve markup for participant selector bar.
Improved layout of participant selector (still more to do though).
Another participant selector layout improvement.
Don't allow null ImageFields, and only photo may be empty (ie. mandate
logo)
Merge branch 'master' into eluminate_participant_views

Conflicts:
	eluminate_web/static/css/style.css
	eluminate_web/static/less/style.less
Merge pull request #38 from jogwen/eluminate_participant_views

Eluminate participant views WIP for issue #7