added handling for directories with no permission

[go-ive]

Hi, I ran into this bug when walking the /etc directory with a non-root user. In this pull request I provide the fix and a test for it. For the test to work, you need the 'test_resource/nopermdir' directory in the base path. The nopermdir directory must be inaccessible (chmod -rwx). I committed it in my fork, but it seems like it won't be merged automatically. Also some JSLint housekeeping for good measure :)