add Nginx.redirect to serve 2 kinds redirect:
1st,serve http 3xx redirection.
2nd,serve nginx internal redirection.
Merge remote-tracking branch 'source/master'
share ngx_mrb_sate_t in each handler
unify style
fix SEGV in mruby_set and mruby_set_inline
Merge pull request #57 from charlescui/master

add Nginx.redirect to serve 2 kinds redirect
Merge pull request #60 from cubicdaiya/feature/shared_state

share mrb_state in each handler