Implement Liquid's whitespace control

[gisforgabriel]

Use whitespace control to make source and output easier to read - https://shopify.github.io/liquid/basics/whitespace/

Also need to upgrade required version of Jekyll to 3.5

[gisforgabriel]

Initial pass complete. However further control will require more tweaking.

• [x] upgrade required version of Jekyll to 3.5 - https://github.com/gisforgabriel/CV-olio/commit/768c977e2847a78b764a116663b33ec135a49381
• [x] intial pass of adding whitespace control - https://github.com/gisforgabriel/CV-olio/commit/8f0290c08673fc46c3bdc55ba3f44d178213c08b