Add tips for admins to home page and magazines page

* Add nicely-styled tips to pages
* Set @tips in a before_filter on all actions
* Use a PageTips class to contain this mess in one place
* Allow specifying a @show_conditional_tips boolean in each controller
  action, for the ones that have conditional tips
Allow toggling whether to show tips at page load

For now, I've added a column to the people table. Yuck. To be removed
whet Typsy.io is a thing.
Add tips when editing pages of issues

I also decided that an editor for any issue of a publication ought to be
able to edit the layout of any other. These are trustworthy people. No
reason to lock it down so tight.
Tips for staff list
Add tips for meetings#index and clean up weird stuff

* Only show magazines for current publication in drop downs
* Clean up print view for meetings#show
* Place tips within the header in the html, since the article is not a
  reliable width
Tips for meetings#show
Add tips for submissions#index
Add tips for submissions#new
Add tips to people#show
Fix RSpec specs; @wip a cucumber feature
Fix confirmations controller by bypassing "set_tips" before_filter

`set_tips` calls "current_person" which does some fancy Warden stuff. The
fancy Warden stuff somehow interacts with the updating of the person
that happens in ConfirmationsController, which resulted in the person
being signed out.
Merge pull request #11 from chadoh/tips_for_editors

Tips for editors