Make it possible to parse 2 element sequences  directly into fusion map

If parser produces 2 element tuple, then fusion::map can be passed
as an attribute to it. Type of first element in produces tuple is used
as a key and second element is a value stored in map.

Few notes how does it work:
- parsing to fusion::map is treated as parsing to container
- special parse_into_container logic call's parser with it's native
  attribute type (fusion::deque<> for sequences) and then updates
  fusion::map with values from it.
Avoid needless construction of sequence<> parser
Added test for fusion::map parsing