add 307 support for ngx.redirect

[RocFang]

Hi, agentzh, I've being reading a book about http and http redirect, so add a 307 redirect support for ngx.redirect.

Appreciate all the work you have done!

[agentzh]

@RocFang Thanks for the patch! Will you mind adding some corresponding test cases to the existing test suite?

[RocFang]

@agentzh
Hi~ It's really hard work for me to make the test suite work fine in my computer, but finally I got it. Please have a check.

[agentzh]

@RocFang Thank you for looking into this! Will you use the reindex script to re-format the .t files you've edited? See https://github.com/agentzh/old-openresty/blob/master/bin/reindex Thanks!

[RocFang]

@agentzh
Done!
So many excellent tools!

[agentzh]

@RocFang Sorry for the long delay on my side. I've just merged a slightly modified version of your patch to git master. Thanks for your contribution!

[RocFang]

Thanks for your work:)