LP#1718301 Offline db connections via promise

LP#1718301 Offline db connections via promise

Refactors offline DB connection call to return a promise, resolved upon
successful connection, instead of polling for a successful connection
within the connect call.

Multiple calls to the main egLoveField connect function will result in
resolvers being linked to the same in-progress promise.

Check for connection errors via the database.connect() reject handler.

Avoid attempts to connect to the offline DB until egLoveField.connectOrGo()
is called the first time.

Signed-off-by: Bill Erickson <berickxx@gmail.com>