Changes to the RoadRunner API

Changes 0.9 -> 0.9.1:

* rr_frame_get_body (): now (correctly) returns "const gchar *" and not "gchar *"

* rr_frame_parse_mime (): new function.

* rr_message_mime_parse_headers (): removed

* rr_message_mime_header_set (): removed

* rr_message_mime_header_get (): removed

* new functions, rr_mime_parse, rr_mime_part_*  (see rr-mime.h): 

Changes 0.8 -> 0.9:

* rr_connection_start should be used to start channels and not rr_manager_start.

* rr_channel_close should be used instead of rr_manager_close_channel

* All methods and variables in RRProfile was moved to RRChannel
  and the RRProfile class was removed.

* Changes in RRChannel:

  - start_initiation renamed to client_init

  - start_confirmation renamed to server_confirmation

  - validate_piggyback ranamed to server_init

  - reply_piggyback renamed to client_confirmation