Add appendFile to the server when the HTTP verb is POST

This complements graphicore/ufoJS#34
Fix a bug when checking if the skeleton is to be deleted
Merge pull request #258 from graphicore/add-append-file-to-REST-server

Add appendFile to the server when the HTTP verb is POST
Merge pull request #259 from graphicore/fix-delete-master

Fix a bug when checking if the skeleton is to be deleted
Merge pull request #254 from rrthomas/master

Add logging
Fix a couple of comment typos
Tell user command-line switch needed for Chromium