Update spacers to increment 1 unit at a time

Currently, our $spacers are set to:

$spacers: (
  0: 0,
  1: ($spacer * 0.5),
  2: ($spacer),
  3: ($spacer * 2),
  4: ($spacer * 3),
  5: ($spacer * 4),
  6: ($spacer * 8)
);

We're jumping from multiplying from 4 to 8 within 1 increment. This MR adds more spacers so we can use values between 32px and 64px