remove scons support as it is not tested, #240

git-svn-id: https://svn.salilab.org/imp/trunk@17320 e91f8c7b-0e32-4433-a9ac-4502d39a4eab
add --test flag to examples when run as tests

They can use this flag to shorten their runtime. See issue #245.

git-svn-id: https://svn.salilab.org/imp/trunk@17321 e91f8c7b-0e32-4433-a9ac-4502d39a4eab