[#60380166] Allow sharding when there are hidden secondaries.

MongoDB's addShard command fails if the connection string includes
hidden members. See <https://jira.mongodb.org/browse/SERVER-9882>.

Omit hidden members from connection strings to work around the
problem.
[#60380166] Bump cookbook version.
Merge pull request #5 from Kabam/fix-sharding-with-hidden-secondaries

Fix sharding with hidden secondaries.