Merged from 'user_access_control.' Users can now only see relevant content when logged out, and can only edit/delete their own information=. Squashed commit of the following:

commit e94ec1dd750ebc3579fa61d76bc988ec1e3d750c
Author: Joshua Lamson <jlamson@mymail.mines.edu>
Date:   Mon Apr 1 00:12:43 2013 -0600

    Added a link to the admin page when logged in.

commit 9a3e157e72c116383d224ef0c85090de8dafe2e3
Author: Joshua Lamson <jlamson@mymail.mines.edu>
Date:   Mon Apr 1 00:02:15 2013 -0600

    Used hack to fix bug (couldn't compare session[:user_id] and user_id, so did User.find_by_id(user_id).id

commit 78b66f23eb8e29785af9490324fdf86a17ba7d07
Author: Joshua Lamson <jlamson@mymail.mines.edu>
Date:   Sun Mar 31 23:58:34 2013 -0600

    Updated show page to not show passwords, and to only show EDIT link if it's you. Also, made link to you like to users/your_id rather than edit

commit 69e45093f0106a7f1616ba26ebbd62e5b22ad218
Author: Joshua Lamson <jlamson@mymail.mines.edu>
Date:   Sun Mar 31 23:53:34 2013 -0600

    Added css for notice and error ids

commit 142cc7dc697270c9c5765200333b5732723c7cd0
Author: Joshua Lamson <jlamson@mymail.mines.edu>
Date:   Sun Mar 31 23:53:13 2013 -0600

    Added links to side bar for users and home

commit 453bc03b4964570a02b8ad459bf207fb081d5fc9
Author: Joshua Lamson <jlamson@mymail.mines.edu>
Date:   Sun Mar 31 23:45:29 2013 -0600

    Replaced notice with a second id, alert

commit e42914e701738ea9040ea009477e35f12c90aefa
Author: Joshua Lamson <jlamson@mymail.mines.edu>
Date:   Sun Mar 31 23:34:43 2013 -0600

    Added logged in check for admin

commit 30790ab71a6c652ddb6127eddadeb74b1495d345
Author: Joshua Lamson <jlamson@mymail.mines.edu>
Date:   Sun Mar 31 23:32:47 2013 -0600

    Added check to see if user being modified is you. Also refactored return flow. edit page is currently unreachable (don't know why)

commit e60d90d4419bdd6343f548a25eb878ab199638b5
Author: Joshua Lamson <jlamson@mymail.mines.edu>
Date:   Sun Mar 31 23:31:48 2013 -0600

    Removed multiple notice hooks and added to application.html.erb

commit 9e90f36518c0fe00b43a2187dae686b5e7a03689
Author: Joshua Lamson <jlamson@mymail.mines.edu>
Date:   Sun Mar 31 23:00:51 2013 -0600

    Added redirect on user index, show, edit, and update if not logged in

commit 7b04b66358f49bccc5bb4bcc235fb37fb5639322
Author: Joshua Lamson <jlamson@mymail.mines.edu>
Date:   Sun Mar 31 22:50:41 2013 -0600

    Modified users page to only show names. Clicking "you" will go to edit, and clicking someone else will go to show