Feature/read from input stream

Hiya Mustafa.

So this pull request is simply to add a new constructor to the 'XSD2OWLMapper.java' class to allow it read from an InputStream (at the moment it only reads from a 'java.io.File').

I need this because I want to read XSD files that are packaged within the 'resources' directory of JARs in other projects. So I need to use 'Thread.currentThread().getContextClassLoader().getResourceAsStream(<resourceName>);' to locate those XSD resources from the classpath, and load them as input streams.

The code changes are minimal, although I had to rework the existing constructor a little so as not to duplicate code between the two constructors that exist now.

Cheers,

Pat.