fix error when mbtiles path contains a space

root cause is that qs.parse() unescapes URL components while url.parse() does not.
https://groups.google.com/forum/#!topic/nodejs/8P7GZqBw0xg
http://nodejs.org/api/querystring.html#querystring_querystring_unescape

lib/mbtiles.js

@@ -31,8 +31,11 @@ MBTiles.schema = fs.readFileSync(__dirname + '/schema.sql', 'utf8');
 // - callback: Will be called when the resources have been acquired
 //       or acquisition failed.
 require('util').inherits(MBTiles, require('events').EventEmitter)
-function MBTiles(uri, callback) {
-    if (typeof uri === 'string') uri = url.parse(uri, true);
+function MBTiles(uri, callback) {    
+    if (typeof uri === 'string') {
+        uri = url.parse(uri, true);
+        uri.pathname = qs.unescape(uri.pathname);
+    }
     else if (typeof uri.query === 'string') uri.query = qs.parse(uri.query);
 
     if (!uri.pathname) {