added test to import all sandbox scripts w/o executing them; see #707
fixed import of all .py scripts in sandbox/
added exec test for all sandbox scripts
added main()
skip sandbox scrip tests in distro
ChangeLog entry for some sandbox testing/cleanup
Merge branch 'fix/test-tempfiles' of github.com:ged-lab/khmer into update/sandbox

Conflicts:
	ChangeLog
Merge branch 'master' of github.com:ged-lab/khmer into update/sandbox
fixed PEP8
Merge pull request #709 from ged-lab/update/sandbox

Added testing to make sure all sandbox scripts are import-able and execfile-able.