Merge pull request #135 from ideal/master

修改daemon和单进程方式的描述，以免产生关于nginx的daemon配置指令和master_process指令有点混淆的歧义。感谢ideal的贡献。
udpate chapter 12
udpate chapter 12, fix typo
Merge pull request #136 from jinglong/master

add content for chapter 12(filter module)
update readme
Merge pull request #137 from jinglong/master

update readme
fix typo

see: https://github.com/taobao/nginx-book/issues/88
     https://github.com/taobao/nginx-book/issues/44
remove autoconf and automake, add make instead
增加ngx_str_t变量定义之后再赋值的一种方法
移除ngx_prealloc()