Make tunnel.handler.Request() raise exceptions

The new tunnel/exceptions.py file contains the tunnel
related exceptions.

The tunnel handler class now raises the good
exception instead of setting its self.error property
to an error message.

=======================================================

removed properties:
-------------------
    self.error

new properties:
---------------
    self.errmsg_request
    self.errmsg_response
* Those properties could be overidden to change default
  exception messages for both RequestError() and ResponseError()
Update tunnel payload builder behavior

It now complies with the new tunnel exceptions feeling
instead of returned an error message for post treatment.

File: src/tunnel/payload.py
Merge branch 'master' of github.com:nil0x42/phpsploit