Seed Flexy - v0.3.2

Updates

• Adds a config for various default gap sizes
• Add gap modifier styles to .o-flexy
• Writes tests

Can be used like:

<div class="o-flexy o-flexy--gap-sm">
  ...
</div>

The gap modifier supports responsive modiifers:

<div class="o-flexy o-flexy--gap-xs o-flexy--gap-lg@md">
  ...
</div>

Quickly 🍐 with @alisdair .

Resolves: #10