Add weighted svc frequency indicator and new param method

Add weighted svc frequency test
Add tests for weighted svc freq
Remove non-DRY portion of stopbuffer params
Fix naming to remove ambiguity
Add low income weighting for avg svc freq
Add i18n for indicators
Add comments and wire up indicators
Merge pull request #290 from moradology/feature/weighted-svcfreq

Feature/weighted svcfreq
Fix missing comma introduced by #290
Merge pull request #305 from flibbertigibbet/feature/fix-missing-comma

Fix missing comma introduced by #290
Paramaterize TransitSystemBuilder to use be able to interpolate stoptimes
Add interpolation to all transitsystembuilder calls in project