Merge pull request #27 from ansell/GITHUB-10

3577999 : Extend Namespaces enum with common prefixes
Added .idea to .gitignore
Changed getBaseIRI to getPrefixIRI

Changed getBaseIRI to getPrefixIRI to be more inline with the OWL 2
spec.  See Table 2 in the spec.
GITHUB-10 : Add RDFa Core Initial Context prefixes