Add error msgs to interactive mode; and fading!
Throw an error if exec is run without a URL
Bit more error handling
Replace %20s with nbsps.

This means chrome URLs will still be legible.
Add a browser check.

This is mainly just for Chrome at the moment.
Ignore .DS_Store!
Bit of housekeeping.

Move unit tests into their own folder; create stubs for missing unit
tests.
Bump spaceReplace up the middleware list a bit
Unit tests for strip op
Merge pull request #100 from andylolz/space-replace

Replace %20s with nbsps in Chrome - refs #87.
none operator unit test