ejs: include fixed

ejs can include external file content into template, but not working in current sourcejs/v.0.4.0
PR changes:
* `filename` parameter added to `options` (https://github.com/visionmedia/ejs/blob/master/ejs.js#L214)
* `getTemplate` logic refactored
As I see, we are getting full file path, not the "filename" that comes from parameter. Please, fix the naming.