Introduce new extension point LdapContextProvider

LDAPUserComponent created LDAP contexts from an LDAPConfig
configuration, which contained sensitive information (user/password)
of the LDAP backend. For certain hosting environmemts this is not
acceptable, but instead credentials must be stored safely outside
a running Skalli instance.

Therefore, the LDAPClient helper class has been removed. Query
related algorithms have been moved to LDAPUserComponent. The
context creation has been moved to DefaultLdapContextProvider,
which implements a new extension point LdapContextProvider.
DefaultLdapContextProvider still creates LDAP contexts based
on configuration information and is retaind for environments,
where storing credentials in the Skalli database is acceptable.

Consequently, configuration attributes related to the LDAP
backend (like url, credentials etc.) have been moved from
LDAPConfig to a new configuration section LDAPServerConfig.

Change-Id: I19e6bf09192fab3a97d36b579106de737ff1ceb5
Signed-off-by: Michael Ochmann <michael.ochmann@sap.com
12 files changed