update ngx_lua to 0.7.19
update lua test cases to version 0.7.19
Fixed: compile on 4.4.5 failed
fixed for nginx standard
Merge pull request #224 from magicbear/master

修正无法在debian 6.0.7下编译 (gcc 4.4.5)
merged the diff between nginx-1.2.7 and nginx-1.2.8
health check: check return value @size of send() or recv()

 * check active close from peer in ngx_http_upstream_check_recv_handler():

   If there is no data to receive, we finish the health check before timeout.
   Note that, without this patch, timeout handler will do it for us.

 * send data later when send() returns 0 in ngx_http_upstream_check_send_handler():

   When the remote tcp receive buffer has been filled up or the local send
   buffer is completely full, send() could easily returns 0.
   In this case, we should send data later just like we handle NGX_AGAIN.

   A good example from nginx is in ngx_mail_send(), which does the same thing
   for `n == 0` and `n == NGX_AGAIN`.
Merge pull request #225 from yaoweibin/tengine_merge_nginx-1.2.8

merged the diff between nginx-1.2.7 and nginx-1.2.8
Merge pull request #226 from chobits/check_size_value

health check: check return value @size of send() or recv()
add keepalive_timeout directive for upstream keepalive module
add test cases for keepalive_timeout directive
fix the wrong number of arguments in keepalive_timeout
Merge pull request #227 from jinglong/keepalive-timeout

add keepalive_timeout directive for upstream keepalive module
add consistent_hash_module for tengine
1. add TFS module docs
2. Bugfix: stat info uncorrect
3. Bugfix: buffer overflow
4. Bugfix: hang up when decline_handler returns error
add forgotten files of last commit.
Merge pull request #234 from zhcn381/upstream

add nginx-tfs documents and bugfix(issue #194)
Merge pull request #233 from dinic/consistent_hash2

added consistent_hash_module
lua模块是支持dso的

Tengine的一大亮点就是LUA模块，DSO也是亮点。
但LUA模块支持模块方式在编译帮助里却没有表现出来，可能对入门学习Tengine的同学不太友好。
误删了一个空格