nginx: redirect * to https, except /dist & *.json

redirect everything on http://nodejs.org to their https
counterparts, except dist and *.json

tested using modified /etc/hosts:

```
curl -v http://nodejs.dev/dist/
curl -v http://nodejs.dev/dist
curl -v http://nodejs.dev/distribution
curl -v http://nodejs.dev/foobar
curl -v http://nodejs.dev/foobar.json
curl -v http://nodejs.dev/dist/123
curl -v http://nodejs.dev/foobar/lala.json
```

part of #68

conf/nginx.conf

@@ -23,11 +23,6 @@ http {
     listen 80;
     server_name  nodejs.org 8.12.44.238 www.nodejs.org;
 
-    ### Re-enable after people update nvm and travis-ci updates?
-    #   location / {
-    #     rewrite ^ https://nodejs.org$request_uri permanent;
-    #   }
-
     access_log  /var/log/nginx/nodejs.access_log main;
     error_log  /var/log/nginx/nodejs.error_log info;
 
@@ -49,6 +44,12 @@ http {
       rewrite ^/documentation/api(.*)$ /api$1 permanent;
     }
 
+    # don't redirect dist to https as it breaks nvm/travis-ci
+    # probably the same is true for json
+    location ~ ^/(?!(dist/|dist$|\.json$)) {
+      rewrite ^ https://nodejs.org$request_uri permanent;
+    }
+
     root /home/node/web/nodejs.org;
   }