Permit a local root to be expressed as file://...

Fixes #128.
Stop setting the default scheme and port.

The scheme is effectively mandatory anyway, since ```pinto```
requires it to distinguish between remote and local repositories.

And now, if you don't specify the port you'll get whatever is
appropriate for the scheme (e.g. HTTP=80, HTTPS=443).

This avoids lots of awkwardness about tring to find a sensible
default. This changes the interface, but it is more consistent
with how other applications work.  Closes GH #136.
Bump VERSION, regen README.
v0.0993

      [INCOMPATIBLE CHANGES]

      - Pinto no longer sets the default port when connecting to a remote
      repository.  So in most cases, you'll have to explicitly add the port
      number to the URI given as the --root.  The default port that "pintod"
      listens on is 3111.  But if you're running "pintod" behind another server
      (like Apache or Nginx) then you can probably omit the port number and
      Pinto will use the default port that is appropriate for the scheme.
      Closes GH #136.  Thanks @spacebat.

      [ENHANCEMENTS]

      - When the repository is a local directory, it can also be expressed
      using a file:// URI.  This applies to both the --root option and the PINTO_REPOSITORY_ROOT environment variable. Fixes GH #128.
Improved locking, to permit concurrent read after commit is complete.

This fixes #142.
Bump VERSION, regen README.
v0.0994

      [ENHANCEMENTS]

      - Improved the locking mechanism so concurrent read operations are
        sometimes possible, especially during the "install" command.  This
        fixes GH #142.
Allow uppercase chars in RevisionID type.
First stab at a revert command.

Needs tests.
Remove debugging code, add TODO notes.
Revision ids weren't being lowercased because I forgot to coerece.
Use get_revision_maybe().
Add --dry-run option to the revert command.
Fix message options on install command.

Added support for --use-default-message (-M) and
removed check for using -m and --do-pull together.
We will just silently ignore the messaging options
if --do-pull is not enabled.
Mention fix for #145 in the change log.
Merge branch 'master' into feature/revert
Mention new revert command in change log.
Mention PINTO_EDITOR variable in docs for the --message option.
POD formatting only.
Just whitespace.