Replaced throwing of std::ios_base::failure with std::system_error. Thanks to Bjorn Reese for suggesting and submitting a patch for this.
thread_source no longer defines its own io_service.

Fixed bad include of Boost system_error.
Merge pull request #50 from BoostGSoC/system_error

Replaced throwing of std::ios_base::failure with std::system_error. Than...