fix(ngShow): Add/remove ng-hide class instead of ng-show class

[bgourlie]

fixes #518

[vicb]

LGTM, @bgourlie could please reword your commits as per CONTRIBUTING.md - and maybe squash the 3 commits.

[bgourlie]

@vicb Done! I'd never done a rebase after having pushed something to github, so that was a nice learning experience!

[vicb]

thanks, conflicts ?

[bgourlie]

Not sure what you're trying to ask...

[vicb]

Just asking if git conflicts were part of your "nice learning xp"

[bgourlie]

Oh, gotcha. Everything went smoothly. I was under the impression that it wasn't possible to rebase once commits have been pushed back to github. It's a good thing to know!

[alexm77]

It is technically possible to force push after publishing your branch, however this is strongly discouraged. It's mostly ok for a branch you know no one else touches, but if you were to branch off someone else's branch and then they did a force push, you'd be screwed, because your branching commit would be gone.
Technicalities aside, thanks for taking the time to fix this.