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
Check dashboard stubs based on page-type

Instead of maintaining a regex of blacklisted files, just assume anything that isn't a dashboard isn't a dashboard.
Added transaction explorer dashboard generator.
Added high volume transaction dashboards.
Fixed description fields for dashboard.

Added notes sections.
Added digital take-up module generator.
Added digital-take-up for high volume services.
Added percentage format to digital-takeup
Fix issue caught by the schema validation.

Only add a related link if one is available in the response.
Fixed weird character issue
Trim whitespace
Changed dashboard-type as per @lennym request.
Updated properties on digital_takeup as per @annaps request.
Tidied up file path declaration
Fixed jshint issues in tools dir.
Lint tools/ directory

This diff only contains whitespace changes.
Update content dashboards

Another round of updates.

* Improve conformance with style guide
* Integrate feedback from Paul Cronk