add the couchbeam:set_values/2 function.

Example:
1> Doc = {[{<<"content">>, <<"this is a funny doc">>}]}.
{[{<<"content">>,<<"this is a funny doc">>}]}
2> couchbeam_doc:set_values([{<<"active">>, true}], Doc).
{[{<<"content">>,<<"this is a funny doc">>},{<<"active">>,true}]}
3> couchbeam_doc:set_values([{<<"active">>, true}], Doc).
{[{<<"content">>,<<"this is a funny doc">>},{<<"active">>,true}]}
4> couchbeam_doc:set_values([{<<"active">>, true}, {<<"type">>, <<"user">>}], Doc).
{[{<<"content">>,<<"this is a funny doc">>},
  {<<"active">>,true},
  {<<"type">>,<<"user">>}]}