Issue 269 - Remove scripts/gh-pages.js script in favour of ghpages package

[Zeouterlimits]

Description:
Issue 269

Switch to ghpages module instead of calling gh-pages directly with a custom script
(aframe-boilerplate also uses ghpages, not a custom script)

Changes proposed:

• Delete script file
• Add 0.0.8, latest ghpages version, as a dev dependency
• Change command to push contents of gh-pages to user or aframe github page

[dmarcos]

Is the funcionality equivalent?

[Zeouterlimits]

I believe so - https://zeouterlimits.github.io/aframe/

[ngokevin]

We use the ghpages script across the boilerplate, most published components in the ecosystem use it, and I use it for my projects too. So it's good, thanks!