health check supported fastcgi
Changed check_fastcgi_params to check_fastcgi_params
Added the documents of check_fastcgi
Fixed the style of fastcgi_check document
Core: slab allocator free pages defragmentation.

Merge nginx official patch: http://hg.nginx.org/nginx/rev/c46657e391a3
Merge pull request #468 from chobits/slab_merge

slab allocator free pages defragmentation
Merge pull request #385 from yzprofile/fastcgi_cheack

health check supported fastcgi
Fixed: fastcgi_check compatible with new health check module
Merge pull request #474 from yzprofile/master

Fixed: fastcgi_check compatible with new health check module