move the banner to the top of the layout so it can show on all pages
render the banner as a notifications bar
add a dismiss button
slide out quicker
add the jquery cookie plugin
fix a bug in the voting dates
allow the dismissed banner to come back when the event changes
add a link to the create session page from the sessions page

This is needed in case the user has dismissed the notifications bar.
split onto separate lines
add an href to the a tags
darken the border of the close button slightly and remove the greenyellow hover colour
revert a change to stop a migration from happening
use the helper to output the event name
change the comment style
inline some variables and rename the data attribute
replace the X with a proper cross
reduce nesting by inverting an if
Merge branch 'shouty-box' of https://github.com/adrianbanks/dddeastanglia into adrianbanks-shouty-box