issue with `default_type` & `type` on 1.5.7

[Jonathan Vanasco]

I recently encountered an issue with a 1.5.7 branch on OSX.  i did not check 1.5.8

The following code will set ALL css/js files as the default_type

    include       /usr/local/nginx/conf/mime.types;
    default_type  application/octet-stream;


The following code works as intended

    default_type  application/octet-stream;
    include       /usr/local/nginx/conf/mime.types;

I haven't had time to test on other versions. 

This could be the intended behavior, but the docs don't suggest that.  usually a default_type only applies when the real type can't be found.