Bodyparser and Test codes

## Parsers
- parses according to content-type

## http.json
- changed content-type from text/json to application/json

## Test codes
- added `supertest` for server testing
- added test for all methods
- still need to raise up branch coverage
I am basically making very large json object which will make http.zip to invoke actual zlib method.
This is just a test fixtures.