Fix Matlab arguments and add description to the ant target
Remove Java objects to prevent warnings in TestCheckJavaPath()

Without these code lines, javaaddpath() & javarmpath() keep on complaining
about existing loci.formats.ChannelSeparator objects even if the readers have
been closed.
Add Matlab and artifacts directories to the path in test-matlab target
Add tools target as dependency of test-matlab
Merge pull request #330 from sbesson/rebased/develop/matlab_target

Test-matlab fixes (rebased onto develop)