Python 3 compatibility.

This version adds compatibility with Python 3.2 and Python 3.3.

Draft 5 and new Builder interface.

• Compatibility with Draft 5 of the JSON HAL standard and backward
  compatibility with Draft 4 and Draft 3.
• New Builder, for creating HAL resources from scratch. Builder gives
  much better performance than Document when building large resources.
• Option to force-wrap links and embedded resources in an array.
• Slight performance improvements to Document's mutation methods.

Draft 4

• Compatibility with Draft 4 of the JSON HAL standard.
• Backward compatibility with Draft 3.

Fixes

• BUG FIX: Links now have a title property instead of a label property.
• BUG FIX: Non-templated links are no longer treated as templates.

API Changes

• Attributes have been renamed to properties.

• The template token for CURIEs is now {rel}, rather than {relation}.

• Improved API for Document().add_link. The second argument can now be a
  URI string or a Document object as well as a Link object. Additional
  keyword arguments are added to the link's properties.

• Document and Link objects are now iterable, yeilding themselves
  exactly once, so single and multiple links for a relation can be treated the
  same with a for loop.

  Example:

  >>> import dougrain
  >>> doc = dougrain.Document.empty("http://localhost/")
  >>> doc.add_link('child', "/1")
  >>> doc.links['child']
  <Link 'http://localhost/1'>
  >>> [link.href for link in doc.links['child']]
  ['/1']
  >>> doc.add_link('child', "/2")
  >>> doc.links['child']
  [<Link 'http://localhost/1'>, <Link 'http://localhost/2'>]
  >>> [link.href for link in doc.links['child']]
  ['/1', '/2']

• Document now treats link relationship types as equal if they are
  equivalent to the same URI when expanded.

  Example:

  >>> import dougrain
  >>> doc = dougrain.Document.empty("http://localhost/")
  >>> doc.set_curie('role', "/roles/{rel}")
  >>> doc.add_link("role:app", "/apps/1")
  >>> doc.add_link("/roles/app", "/apps/2")
  >>> doc.add_link("http://localhost/roles/app", "/apps/3")
  >>> [link.href for link in doc.links["role:app"]]
  ['/apps/1', '/apps/2', '/apps/3']
  >>> [link.href for link in doc.links["/roles/app"]]
  ['/apps/1', '/apps/2', '/apps/3']
  >>> [link.href for link in doc.links["http://localhost/roles/app"]]
  ['/apps/1', '/apps/2', '/apps/3']

Initial Release

0.1

Fix packaging.