Explore the need for height/width on inlined SVG's

[crgeary]

I made a PR (#136) to fix issue #123 which essentially consisted of removing the height/width from the inlined SVG element. According to this CSS Tricks article on SVGs the width/height attributes are not useful for scaling inline SVGs, and instead we should set the aspect ratio with viewBox.

The 2 solutions that I can think of would be:

1. Manually remove width & height attributes from the SVG files.
2. Use a gulp task to remove width & height attributes on build.

The gulp inline package that we're using supports SVG transformations via options. I would guess, this is something that would help, but I'm not sure.

I see this being similar to #104 so solving one may solve the other 🤞