Remove external URL references

[tharmstrong]

Material Design Lite:

• example: https://code.getmdl.io/1.3.0/material.indigo-blue.min.css

Masonry:

• example: https://unpkg.com/masonry-layout@4/dist/masonry.pkgd.min.js

[tharmstrong]

This is needed for:

• enhanced page speed
• to allow bots to index better
• higher search score

[tharmstrong]

done