First step of a larger health-lifesci cleanup cycle.

Intend to decrease confusion and incorrect usage of properties. Also frees these property names for future use.

Examples:
http://schema.org/action
http://schema.org/background
http://schema.org/cause
http://schema.org/cost
https://schema.org/function
https://schema.org/indication
https://schema.org/origin
https://schema.org/outcome
https://schema.org/overview
https://schema.org/phase
https://schema.org/population
https://schema.org/purpose
http://schema.org/source