Adding column layout according to Material guidelines:

- Maximum of 3 columns in "web" layout, with 360px fixed width columns, 40px gutters and excess padding left and right.
- 2 columns in "tablet" layout, with variable size columns and 24px gutters.
- 1 columns in "phone" layout, with 16px gutters.
Looks like we moved away from that file in this branch, and I can't find an equivalent :-/
Sounds like a good idea for a future fixit pass, though.