Use real refresh token

The first refresh token I received during initial testing was hard
coded for rapid prototyping.  There's now enough infrastructure to use
the real refresh token.  This has the added benefit of actually
working :-)
Improved debug formatting

Add some whitespace between each task that we process.  This makes it
easier to see what's happening.
Delete tasks in Future after creating in Today

When a task needs to be moved from the Future list to the Today list,
we must create a new copy of the task in Today (Google has no API for
moving tasks between lists).  After inserting the new copy, we need to
delete the old copy, or we'll copy it the next time too.
Move Prolog files under prolog directory
Helper for development mode
Consolidate all datetime code

The eventual goal is to separate this code into a new module so many
projects can use it.
Document template_applicable/2