Update pom.xml

The code actually doesn't need JDK 1.7 at all, and so a library should only stipulate the lowest JDK version it actually needs to compile, as projects dependent on that library may be using older JDKs.
Update XSD2OWLMapper.java

Spaces in the values of enumerations will cause the generation of an invalid URI in the output RDF serialization.
Merge pull request #2 from pmcb55/Jdk-6-and-spaces-in-enum-values

Jdk 6 and spaces in enum values