SI-6669 Add . to the default scalap classpath

The default classpath for scalap did not include '.' which made it
behave differently from javap in an annoying way. This commit adds
it to the default. Also included is a test to make sure it's in
the default but does not corrupt a user specified classpath.
Merge pull request #2031 from JamesIry/2.10.x_SI-6669

SI-6669 Add . to the default scalap classpath