Segment job ads by section

Section in which requested page lies is used to choose a suitable job ad.
Replace all whitespace in keywords rather than just first instance
Refactor
Merge remote-tracking branch 'origin/master' into kc-job-sections
Add section -> job sector mappings
Render job commercial components as json
Merge pull request #2233 from guardian/kc-job-sections

Commercial: Job Ads Targetted At Sections