do not test for ENOENT errno

the errno property for ENOENT changed from 34 to -2 in node 0.11
minor: pretest `npm run clean`
be more specific form `git clean` glob

for some reason `git clean -dfX **/artifacts` proceeded to delete the
node_modules dir on travis/linux:

    > mojito-cli-create@0.0.7 clean /home/travis/build/isao/mojito-cli-create
    > git clean -dfX **/artifacts

    Removing node_modules/

using a less magic glob to avoid
Merge pull request #25 from isao/fixtest

do not test for ENOENT errno