remove inherited properties from GSJS catalog meta items

Fixes trello#24.
add an API function for retrieving the GSJS config

Fixes trello#25.

The HTTP API needs this to get information about skills, achievements
etc.
Merge pull request #27 from yelworc/trello#24_catalog-items

remove inherited properties from GSJS catalog meta items
Merge pull request #28 from yelworc/trello#25

add an API function for retrieving the GSJS config