Refactor _all_docs/_temp_view request preparation

Eventually fixed sending list of `keys` for temporary view within
the body instead of query parameters.
Add missed `att_encoding_info` query parameter for _all_docs
Implement /db/_design/ddoc/_view/viewname API call
Refactor views helper
Implement /db/_design/ddoc/_list/listname API call
Implement /db/_design/ddoc/_show/showname API call
Implement /db/_design/ddoc/_update/updatename API call