1 delete some dead code.
2 fix some code style.
3 modify tfs_upstream directives and document.

tfs_upstream example:

    tfs_upstream tfs {
        server 127.0.0.1:6100;
        type rcs;
        rcs_zone name=tfs1 size=128M;
        rcs_interface eth0;
        rcs_heartbeat lock_file=/logs/lk.file interval=10s enable=1;
    }

    location / {
		tfs_pass tfs://tfs;
    }
Year 2013.
fix code style.
 remove dead code.
Merge https://github.com/taobao/nginx-tfs

Conflicts:
	conf/example.conf
	src/ngx_http_connection_pool.c
	src/ngx_http_connection_pool.h
	src/ngx_http_tfs.c
	src/ngx_http_tfs.h
	src/ngx_http_tfs_block_cache.c
	src/ngx_http_tfs_block_cache.h
	src/ngx_http_tfs_data_server_message.c
	src/ngx_http_tfs_data_server_message.h
	src/ngx_http_tfs_duplicate.c
	src/ngx_http_tfs_duplicate.h
	src/ngx_http_tfs_errno.h
	src/ngx_http_tfs_json.c
	src/ngx_http_tfs_json.h
	src/ngx_http_tfs_local_block_cache.c
	src/ngx_http_tfs_local_block_cache.h
	src/ngx_http_tfs_meta_server_message.c
	src/ngx_http_tfs_meta_server_message.h
	src/ngx_http_tfs_module.c
	src/ngx_http_tfs_name_server_message.c
	src/ngx_http_tfs_name_server_message.h
	src/ngx_http_tfs_peer_connection.c
	src/ngx_http_tfs_peer_connection.h
	src/ngx_http_tfs_protocol.h
	src/ngx_http_tfs_raw_fsname.c
	src/ngx_http_tfs_raw_fsname.h
	src/ngx_http_tfs_rc_server_info.c
	src/ngx_http_tfs_rc_server_info.h
	src/ngx_http_tfs_rc_server_message.c
	src/ngx_http_tfs_rc_server_message.h
	src/ngx_http_tfs_remote_block_cache.c
	src/ngx_http_tfs_remote_block_cache.h
	src/ngx_http_tfs_restful.c
	src/ngx_http_tfs_restful.h
	src/ngx_http_tfs_root_server_message.c
	src/ngx_http_tfs_root_server_message.h
	src/ngx_http_tfs_server_handler.c
	src/ngx_http_tfs_server_handler.h
	src/ngx_http_tfs_tair_helper.c
	src/ngx_http_tfs_tair_helper.h
	src/ngx_http_tfs_timers.c
	src/ngx_http_tfs_timers.h
	src/ngx_tfs_common.c
	src/ngx_tfs_common.h
Merge pull request #6 from monadbobo/new_upstream_directives_fix2

modify tfs_upstream directives and document