Files library needs updates

The files library should be extended to support directories.

In order to do this, the following changes need be made:

• When creating files on disk from embedded content (or otherwise) leading directories should automatically be created

Also the following steps need to be added:

• given a directory {foo}
• when I create directory {foo}
• when I remove directory {foo} (note this should do a recursive removal)
• then directory {foo} exists
• then directory {foo} does not exist
• then directory {foo} is empty
• then directory {foo} is not empty