fix Nullpointer Exception when using -l jsp

Hi guys,
when using PMD to check some JSP I noticed a NPex:

Exception in thread "main" java.lang.NullPointerException
        at net.sourceforge.pmd.lang.LanguageVersionDiscoverer.setDefaultLanguageVersion(LanguageVersionDiscoverer.java:25)
        at net.sourceforge.pmd.cli.PMDParameters.transformParametersIntoConfiguration(PMDParameters.java:121)
        at net.sourceforge.pmd.PMD.run(PMD.java:356)
        at net.sourceforge.pmd.cli.PMDCommandLineInterface.run(PMDCommandLineInterface.java:158)
        at net.sourceforge.pmd.PMD.main(PMD.java:344)

The reason is that as the default version (Java 7) is not found in the JSP language no default language version is found for JSP. I could not workaround this as there is no version I can specifiy for JSP. I changed the code to use the default version in this case.

Greetings