Sparqlwrapper

-----------------
- Added some support for SPARUL
- Improved HTTP related code
- Many other minor bugs fixed

-----------------
- Remove pyxml dependency. Instead, use xml.dom.minidom
- Updated setup installation (added rdflib dependency)
- Updated example.py (added XML, N3 and RDF examples)

-----------------
- Remove simplejson dependency for python => 2.6 version
- Added feature to choose the json module to use

-----------------
- Added a new method to add custom parameters (deprecated old way to do it)

-----------------
- Updated setup installation
- Patched to work with JSON in Python>=2.6

-----------------
- Allowed non-standard extensions (such as SPARUL).
- Exceptions fixed.
- Added another example.