docs for internal api (only the really basics)
revamped PekErrorCode (#41)

from now on error codes have two parts (type + code)
renamed old error codes for clarity
adjusted the code where needed
handling method not allowed exception and returin HTTP 405
fixed: request wrapping when body is empty

removed resteasy specific error handling and dependency
using the NotFoundException's original response as a base
following the file naming convention for exception handlers
added logging for application exceptions
Merge pull request #112 from kir-dev/error-reporting

API error reporting