Add integration test with OpenLDAP to Travis matrix
Add integration test with OpenLDAP to Travis matrix

bkeepers/ruby-net-ldap,bkeepers/ruby-net-ldap,cloudvolumes/ruby-net-ldap,cloudvolumes/ruby-net-ldap,astockwell/ruby-net-ldap,javanthropus/ruby-net-ldap,astockwell/ruby-net-ldap,javanthropus/ruby-net-ldap