Default values in journey-series collection

When backdrop does not have any hits at all for one of the steps in a journey collection it returns no data point, which means the graph bar is rendered with a "no data" label.

If we have data for some of the steps, then assume that the value for the missing step should be zero, rather than "no data".
Merge pull request #413 from alphagov/bugfix/journey-module-missing-data

Default values in journey-series collection
Refactor get tagline script so it doesn't require modules to have a dashboard type of other

We want to be able to have a configured tagline without forcing a specific dashboard type, so we add a fallback of just having a tagline property on the model.

Ideally we'd also get rid of the "other" stuff, but it stays for backwards compatibility.
Add support for high-volume-transaction option as dashboard-type
Merge pull request #414 from alphagov/refactor/get-tagline

Refactor/get tagline
Update experimental site-activity dashboards

This update includes many small fixes requested by the designers,
mostly language fixes and small functionality fixes.
Merge pull request #411 from pwaller/update-content-dashboards

Update experimental site-activity dashboards
Add "normalisation" option to "percent" formatter

This is so that values represented as 0-100 in backdrop can be correctly
formatted.
Use 'normalisation' to correctly format percentage

... in content dashboards
Add test for percentage normalisation
Add high volume transaction dashboard type to allowed list
Add content dashboard type to allowed list
Merge pull request #416 from pwaller/percentage-normalisation

Add 'normalisation' parameter to 'percent' formatter
Merge pull request #417 from alphagov/feature/dashboard-types-enum

Feature/dashboard types enum
One fewer bit of requirejs running in a server-only environment
Move no realistic dashboard into experimental directory

We have to manually blacklist NRD from all the automated tools we use for dashboards.
Moving it into `experimental` allows it to be automatically ignored from any lists we create, and probably is a more sensible place to keep it generally since it's only used for development.
Add script to generate services list from dashboards configs
Remove services.json from version control

It's generated automatically now, so doesn't need to be in git.
Generate services.json as part of app startup