[#1446] Require ckan.site_url when using the DataPusher
[#1446] Better defaults for DataPusher config options + docs
[#1446] Clarify DataPusher issues in docs
[#1446] Remove SQLite urls from template ini file
[#1446] Enable DataPusher for private datasets

There's no need to prevent the import to the datastore on them, as the
datastore will manage the authorization, and logged in users still
expect these files to get imported to the DataStore.
[#1446] Remove misleading datastore warning in docs