UI color updates

[birdofpreyru]

@Dara-K:

Vic told me he updated the color variables for the TC site: https://github.com/appirio-tech/tc-ui/blob/feature/connectv2/src/styles/_variables.scss
Can you do the updates to be reflected here as well: https://community-app.topcoder-dev.com/examples/color-mixins ?