change to use a typeclass for response bodies

- remove ToResponse
- first pass of ToResponseBody - see comment for todo
- add tools for Accept header based content negotiation
- move things around
- add new responding tools
fix the ToResponseBody definition

- make ToResponseBody instances produce ByteStrings instead of some
  convoluted thing
- update everything to work with that definition
- update some project description stuff
add text and html formatting of error reports

- remove original, lawless ReportableError typeclass
- add new one focused on serialization wrt content negotiation
- plug it into handlers etc
- add more tools for matching and sending media types
- add simple, kinda stupid html and plaintext formats for error reports
- make error report the main instance of ReportableError
fix comment in Response.hs
Merge pull request #1 from raptros/0.2.0.0

change much of the way respond enables response generation