plug content explorer prototype into dashboards

@abersager
fix format-success test, disable outdated test
remove coloured squares and add scale labels to x axis
Formatter functions wrapped into js initialiser

  This allows for private functions and variables

@maxfliri
Improve code readability

@maxfliri
Make "copy" image resize nicely + change it to svg

@maxfliri
@pbadenski
Render fonts correctly in SVG graphs

@robyoung
@pbadenski
Add fonts directory for .ttf NTA.
Rearrange functions to avoid scoping issue

page.evaluate executes the function in the context of the page rather than the PhantomJS script.

@pbadenski
@robyoung
Render NTA fonts on the graph images

NTA tabular numbers do not work yet, standard nta font is used for everything.

@norm
@pbadenski
Updating the annotations for inside gov.

@gtrogers
... and updating updated_at field
Upgrade Plek to 1.1.0
Use Plek to find recorder locations

FACTER_govuk_platform does not work on the new environment.
Expose content engagement detail endpoint

@maxfliri
@pbadenski
adopt new json format, update fixtures, use actual data for insidegov
overlay position for content explorer
content explorer overlays take svg scale factor into account.

@abersager
bugfix: increase circle stroke width on hover

@abersager
add 'summary' entry to filter dropdown. fix dropdown navigation.

@abersager