import to jekyll from unzipped posterous archive directory
small fix - restrict post file search to the posterous archive posts/ subdirectory
Added a comment block to posterous-archive.rb, containing usage instructions.
Changed posterous archive importer class name to avoid conflict with existing posterous importer. Modularised posterous archive importer to allow for easier testing. Added a couple of unit tests for posterous archive importer.
HTML formatting is preserved when post content is extracted from posterous html files
Merge pull request #12 from pauldmccarthy/initial-migrator-import

Import to jekyll from unzipped posterous archive directory