Fix Configuration Duplication on Page Creation

Turn pageflow.Page#defaults into a function. Otherwise new pages share
the same object as their configuration attribute causing modification
of the default page configuration when page is edited.
sort files by lowercase file names

fixes #86

otherwise lowercase files come last.
Merge pull request #103 from tf/dup-page

Fix Configuration Duplication on Page Creation
Merge pull request #105 from tf/files-order

Sort Files by Lowercase File Names
Local Variable `entry` for `published_entries_exhausted` Partial