fix: crash when express views set to string

src/express.js

@@ -1,19 +0,0 @@
-const Liquid = require('..');
-
-module.exports = function() {
-    var engine = Liquid({
-        root: '/root/',
-        extname: '.html'
-    });
-
-    function express(filePath, options, callback) {
-        fs.readFile(filePath, function(err, content) {
-            if (err) return callback(new Error(err));
-            // this is an extremely simple template engine
-            var rendered = content.toString().replace('#title#', '<title>' + options.title + '</title>')
-                .replace('#message#', '<h1>' + options.message + '</h1>');
-            return callback(null, rendered);
-        });
-    }
-    return express;
-};