Backport Adapter#ldap_search from EE
Backport Adapter#ldap_search from EE

8thcolor/eurucamp2014-htdsadr,8thcolor/rubyconfau2015-sadr,8thcolor/eurucamp2014-htdsadr,8thcolor/rubyconfau2015-sadr,8thcolor/eurucamp2014-htdsadr,8thcolor/rubyconfau2015-sadr