JIRA calls findAllPrincipalNames(), then iterates over each username, asking for the user object.

Since findAllPrincipalNames() is implemented as a call to searchPrincipals() which fetches all the user details, we should optimise this code path by adding replacing the code that performs this in the crowd-integration-client with a call to searchPrincipals().

This will make life much better for LDAP (particularly AD), and custom directory users.