Dexterity support, use of portal_type and more changes

We've been working on some improvements for a client and all of them are included here. The initial aim was to support Dexterity types, but we found some other issues, and tried to fix them:

- Support for Dexterity content-types and plone.namedfile based blobs
- DeploymentSteps (those that can be written by a developer) are now executed in a predictable way: the order in which are stated in the staticdeployment.ini file.
- An option to deploy all content below a given path. Useful to deploy /en in a multilingual environment or a subsite in a multisite environment.
- The deployment of just one object using the parameter only_object works now as expected.
- Some fixes in the HTML parser. The existing one "ate" all my content.
- Added more logging.
- Be predictable when creating the static files folder.

Do not hesitate on commenting, and if you want, I can merge the pull request fixing the conflicts

@codesyntax @libargutxi