Update rackup config to include logging

Redirect stdout and stderr to a log file by default.
Add os detection methods

Fixes an issue on windows, where we can't assume that weasyprint's binary
in the path actually works because of Heliotech's environment, so launch
the script via python, which works.

Fixes another issue where the temporary file for pdf is possibly composed
of non-printable characters, which is fine on UNIX machines, but windows
will likely fail. So we name the file using hexadecimal characters, which
are printable on NTFS.

Add dependency on haml and logger in preparation for editor additions.
Add basic Editor support

Fix a number of minor issues and tidy up some settings.

Add a basic editor on /editor, embeds an instance of Ace into
the browser window and hooks up some simple jquery/javascript
to allow for rendering to html as a preview system.
Remove Holmes from the project

Was supposed to be the integrated mail server, but now not
needed as the REST service is accessible on live through
http.