DefaultPackageFilter should only consider .class files

[p91paul]

Classpath may contain files with extensions which are not .class.
For example my classpath contains .xml files (because MyBatis).

Currently ReflectionUtils.removeClassSuffix is called, that removes the .class suffix; however it should filter to consider .class files only before doing that.

Right now my.package.File.xml becomes my.package.Fi and that triggers an error when Class.forName is called on it.