update ngx_lua to 0.7.19
update lua test cases to version 0.7.19
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
Merge pull request #235 from higkoo/master

added description for Lua module in configure
Merge pull request #216 from jinglong/ali

update ngx_lua to 0.7.19