Fix/kissmetrics props

@yields @ianstormtaylor this is the one that will need a migration...

there are a few changes here, as requested by master of kiss @DirtyAnalytics:
1. page category makes no sense
2. critical page properties are url, path and title... should be prefixed by category/name of page
3. events need prefixed properties

just getting this rolling, i assume we'll need to adjust things. in particular i'm unsure of how to handle category/name properly for page. i think @DirtyAnalytics has a point that page category doesn't make a lot of sense as a top-level argument.