support for including a fileset for px:html-to-fileset
html and dtbook to fileset: fixed original-href, ocf finalize: custom base

dtbook-fileset: added original-href
ocf finalize: custom base
html-to-fileset: fixed original-href
commented out mock function reference
Merge pull request #25 from daisy-consortium/html-to-fileset-optionally-provide-fileset

support for including a fileset for px:html-to-fileset