Set cookie to supress tour on popup close

Previously, the cookie set to supress showing the tour is only set when the
user clicks the close button on the final guider window. It is now set
when the user clicks the final close button, or the "X" icon in the
upper-right-hand corner of any of the tour popups.

This was annoying me when doing integration testing.  Furthermore, I believe
that users don't want to see the tour again if they close out of it early.
The tour remains accesible through the tour icon in the help drawer.

This commit also includes a cleanup of the guider construction by creating
an object with default options for guider construction. This is applied to
the arguments to ``createGuider`` by using ``_.defaults``.

Closes #697
Add close icon to alerts

Add a close icon that will remove an AlertView's element from the DOM.

Move the fade out functionality inside AlertView.

Add an onClose callback to the options of AlertView.

Set a cookie when the unsupported browser message is closed so the message
is not shown again when the user has closed it.

Addresses #548
Break alert management into a separate view

Alerts are now managed by AlertManagerView, instantiated by AppView instead
of AppView itself.
Better throttling of alert messages

Instead of only tracking the last alert messages, keep track of all visible
messages and only show a message if it isn't already visible.  This prevents
the stack of alerts that occurs when the layout is changed.

Also add a ``sticky`` option to the ``showAlert`` method that keeps an alert
message at the top of the list. This improves the behavior of the unsupported
browser message.

Addresses #548
Add dev section to changelog

This is a place to stage changelog messages for the current development
branch.  It avoids having to keep track of version numbers as hotfixes come
in.
Remove style-old.css from repo.
Merge branch 'hotfix-700-switch_geocoder' into develop

Conflicts:
	README.rst
Adjust alert dismiss button markup/style

Use a button element for the dismiss button instead of a span.  Also,
position the dismiss button to the far right of the alert bar instead of
just to the right of the text.

Also remove the 1px white border from the builder header.

Addresses #548
Update required version of django-filer

Since the blocking issue is no longer relevant, use the stable version
from pypi instead of the development version on GitHub.
Merge pull request #701 from patternleaf/develop

Remove style-old.css from repo.
Don't show alert in alert bar on save

Instead of showing an alert in the alert bar when the story is saved,
just flash the last saved message in the upper-right-hand corner.

Also, flash the last saved message when assets are saved.

Addresses #548
Break alert colors into variables
Green background and text for last saved message

Addresses #548
Remove unused import
Wire up links to news items on homepage

Previously, there was no detail view for news items, so the homepage slider
items had non-functional title links.  With the content reorganization
(see f091a9e713331918782d89f1a15c3321aea4f77e), there is now a detail view
for news items, so the links in the homepage slider can now be wired up.

This also fixes a typo in ``NewsItem.get_absolute_url`` where the code
tries to reference ``self.last_updated`` instead of ``self.last_edited``.

Addresses #703
Merge branch 'hotfix-703-news_item_links' into develop

Conflicts:
	README.rst
Merge branch 'develop' into 548-more_subtle_save_alerts
Toggle save button style on save

Instead of flashing a last saved timestamp, change the button color to
green and the text to "Saved".

Addresses #548
Refine save button behavior

Toggle the ``disabled`` attribute on the button when it is displaying the
"Saved" message.

Use a modified version of the
[JavaScript Pretty Date] (http://ejohn.org/blog/javascript-pretty-date/)
function to format the timestamp in human readable form.

Use ``setInterval`` to continually update the timestamp.

Remove methods and code which wrote the timestamp to a separate element.

Addresses #548
Move search bar to top of map in explorer (#559).

Also tweak some spacing. May fix (though not confirmed) part of #501.