Use the end date to plot data with period of a week

Need to subtract a day from the tick labels because week periods are shown as ending on the Sunday, though `_end_at` property represents midnight on Monday.
Remove reliance on internal structure for emptiness test

By using `isEmpty` instead of querying the internals of the collection we can reduce the coupling between the collection's data-structure and the view.
Remove stacks from site-activity dashboard
Merge pull request #595 from alphagov/enhancement/week-graph-periods

Use the end date to plot data with period of a week
Update spec.realtime.js

Fix typo
Fix crashing bug in volumetrics number view

When the app can't connect to a data source, it crashes. It should
handle that gracefully.
Fix crashing bugs in availability collection

When the app can't access the data API, it should fail gracefully
instead of crashing.
Let the app work with pm2
 - https://github.com/Unitech/pm2/issues/343
 - Basically requirejs
 - We need to set the baseUrl before we try and require the config file inside requirejs
Update format of axes for content dashboards.

Graphs that have been unstacked also need axes formatted as percent
rather than integer, so that their tables display correctly.
Merge pull request #597 from alphagov/fix-crashing-bugs-no-data

Fix crashing bugs when there's no data
Merge pull request #604 from alphagov/feature/pm2-compatible

Let the app work with pm2
Merge pull request #601 from alphagov/refactor/the-matrix

Remove reliance on internal structure for emptiness test
Merge pull request #602 from alphagov/feature/unstack-graphs

Remove stacks from site-activity dashboard
Remove "digital" from waste carriers cost

As requested by @cliffshepp.
Remove bodyparser as we never use it EVER!
Removed method-override as we never use it.
Merge pull request #605 from alphagov/feature/remove-body-parser

Remove bodyparser and method-override as we never use them EVER!
Remove multi-stats module from no-realistic-dashboard.

This module is no longer used on the housing dashboard, and not
compatible with the Refactor of Doom. Remove it so that we can
still use no-realistic-dashboard.
Remove multi-stats module from codebase.

We no longer use this module anywhere and we have no plans to use
it anywhere. So we have agreed to remove it entirely.

Some of the sub-views used by multi-stat items were actually used
elsewhere in the codebase, so I have kept these but moved them
out of multi-stat-specific directories. The affected views are
sparkline, headline and delta views, and these are used by the
user satisfaction and realtime modules.

Note that spec.realtime.js now throws a D3 console error in the
Jasmine tests. I'm not sure why this is: the graphs are rendering
fine in the browser.