Changed billion abbreviation from 'b' to 'bn'.
Merge pull request #448 from alphagov/bugfix/billion-abbreviation

Changed billion abbreviation from 'b' to 'bn'.
Added "About the data" for transactions-per-quarter
Merge pull request #452 from alphagov/enhancement/about-info-on-txperquarter

Added "About the data" for transactions-per-quarter
Add stub and KPI modules for IPO patent fee dashboard
Amend type of IPO dashboard to transaction