Merge pull request #58 from sansr/master

Include Sandra_Saez.ttl
Adding RDFs
Merge pull request #59 from etsiinf/master

Adding RDFs
Sergio Conde: Added graph to ttl exercise.
Sergio Conde: Added graph to xmlrdf exercise.
Sergio Conde: Added xmlrdf to graph exercise.
Sergio Conde: Fix indent...
Merge pull request #60 from skgsergio/master

Sergio Conde: Exercises from assignment 2.
Include Sandra_Saez_graph.png (Stickynote)