Merge pull request #412 from tosnoz/libevent_evhttp

Libevent evhttp implemented
add compile switch for not supported version evhttp_connection_get_bufferevent()
Merge pull request #414 from tosnoz/libevent_evhttp

add compile switch for not supported version evhttp_connection_get_bufferevent()
fix coding style
fix build error
Merge branch 'master' into libevent