Included templates now have their respective feature processed

Package
* bumped version to 0.1.0 (from 0.0.1)

Template
* the preparation of features has been moved to a separate function
* preparation is now recursive (and async) as feature may be
manipulating the internal DOMDocument (e.g. the ‘include’ feature may
bring in a template with its own blocks, includes, etc
* cleaned up old clean up functionality as this is now taken care of by
the DOMSerializer
+ added public path method which allows for direct access to the DOM
(this may require exposing the ‘prepare’ function aswel).

TemplateFeatureInclude
* the feature element itself is now properly removed when the
preparations are done

DOMSerializer
* renamed toString method to serializeToString as per DOM specification