Commit com.ibm.wala.analysis.reflection.ext.* for pull-request

Just for reviewing it. There are many context-classes in Wala an perhaps its possible to achieve the same thing without defining a new context. For instance, if i was able to somehow pass both a JavaTypeContext and a CallerSiteContext then I could perhaps access the constant value in the context interpreter. This code is untested
as i ripped it out of a larger piece of work.