Add support for a path in host

[pietervandereems]

Based on #128
We use this because our couchdb is behind a proxy.

[pietervandereems]

This is needed for the changesfeed:

diff --git a/lib/cradle/database/changes.js b/lib/cradle/database/changes.js
index fe0ba8f..b8bcd7a 100644
--- a/lib/cradle/database/changes.js
+++ b/lib/cradle/database/changes.js
@@ -35,7 +35,7 @@ Database.prototype.changes = function (options, callback) {
             auth = this.connection.auth.username + ':' + this.connection.auth.password + '@';            
         }
         
-        options.db = protocol + '://' + auth + this.connection.host + ':' + this.connection.port + '/' + this.name;
+        options.db = protocol + '://' + auth + this.connection.host + ':' + this.connection.port + (this.connection.path_prefix || '') + '/' + this.name;
     }
         
     feed = new follow.Feed(options);

[panuhorsmalahti]

1. Fix conflicts
2. Add test for the new feature
3. Add documentation for the new feature (basically a sentence or two in the readme)
4. Remove all the extra stuff from the PR (like the package.json changes and stuff), as it seems you've updated the PR when you only wanted to make those changes to your own fork
5. Rename path_prefix to pathPrefix

With these changes I'm okay for merging this.