If WordPress is in subfolder, then change nginx configuration automatically

[anugupta]

Currently, if WP is installed into a subfolder (eg /vagrant/blog), then we have to manually edit nginx/default.conf, uncomment the location block and update it with the folder name.

We should be able to do this automatically:

if wp_path is set to a subfolder in settings.sh, then add a location block into nginx/default.conf automatically.