Added optional ssl (cherry-picked from 36536e7 by kazuho)

To use it add the ssl certifcate, key and uncomment:
//ssl_ctx = h2o_ssl_new_server_context("server.crt", "server.key", h2o_http2_tls_identifiers);
Conflicts:
	src/main.c
remove hard-coded initialization of logger, should be initialized using configuration directives (TODO)
change comment to C-style
add optional support for HTTPS to the server (commented out by deafult, merges branch 'kazuho/pr/35')