Increased connection timeout for CSW harvest requests

Some CSW services are unable to process requests in 10 seconds (default of owslib.csw.CatalogueServiceWeb).
Merge pull request #262 from milokmet/master

Increased connection timeout for CSW harvest requests
Empty queriable columns creator, publisher, contributor

Fixes #263
Merge pull request #264 from milokmet/fix263

Empty queriable columns creator, publisher, contributor