Add move constructor and move assignment to boost::asio::io_service

[martin.desharnais@…]

With the inclusion of type inference in C++11, I got the habit to use it for every variable:

auto i0 = 10;
auto i1 = int(10);
auto i2 = foo();
// etc.

Unfortunatly, this is not possible with boost::asio::io_service since it is noncopyable and does not provide move constructor and move assignment.

// error: use of deleted function ‘boost::asio::io_service::io_service(const boost::asio::io_service&)’
auto io_service = boost::asio::io_service();

[chris_kohlhoff]

This is by design.