update _test_single_term() for dynamic connectivity terms
update _test_single_term() for dynamic connectivity terms

- test_term_call_modes() tests pass for dw_contact

rc/sfepy,BubuLK/sfepy,sfepy/sfepy,lokik/sfepy,vlukes/sfepy,lokik/sfepy,lokik/sfepy,BubuLK/sfepy,vlukes/sfepy,BubuLK/sfepy,sfepy/sfepy,rc/sfepy,vlukes/sfepy,rc/sfepy,sfepy/sfepy,lokik/sfepy