move the render of the partial outside of the form

Having it inside seems to cause the rendering to put the submit button outside of the form, meaning it does nothing when clicked on
move the spacing from the voting buttons to the session titles
don't include the controls' text in the search
add javascript to dynamically add hover behaviour to all gravatar pictures
move the gravatar js include to the master layout so that every pages loads it
add the gravatar js to all of the admin pages
Merge pull request #304 from adrianbanks/fix-session-deletion

Fix session deletion. This was reported by a user when trying to delete their session.

Having the render partial inside the form seems to cause the rendering to put the submit button outside of the form, meaning it does nothing when clicked on.
Merge pull request #305 from adrianbanks/voting-button-styling

Move the spacing from the voting buttons to the session titles.

A previous change set the voting button space to be a fixed width so that when placing a vote and the button text changes size causing the button to get wider, the session title doesn't then move around. This causes the edit and delete links that appear on a user's own sessions to have excessive spacing between them and the voting button. This change puts a margin on the right of the session title instead to achieve the same result without the unwanted side effects.
Merge pull request #306 from adrianbanks/fix-searching-in-admin-section

Don't include the controls' text in the search.

The search box was searching on the text of the controls, meaning that if you typed "edit", all rows matched.
Merge pull request #309 from adrianbanks/hover-profile-picture-popup

Add a hover behaviour on all gravatar images to pop up a larger version
add a new calendar event to the conference
add new checks to the calendar entries
show the voting link up until the agenda is announced
use the common coding style
Merge pull request #310 from adrianbanks/show-stats-after-voting-closes

Show stats after voting closes