Optimise SVG and gulpfile

- all svg optimised
- regenerates base64 data URI in css

Signed-off-by: Jérôme Coupé <jercoupe@gmail.com>
Better SVG workflow

- modify SVGO plugins in gulp config so SVG are less borked
- smaller / leaner SVG files

Signed-off-by: Jérôme Coupé <jercoupe@gmail.com>
Simplified grid

- now only 12 and 10 columns grids: generated is CSS smaller
- modifed HTML code to reflect new grid

Signed-off-by: Jérôme Coupé <jercoupe@gmail.com>
New Image for antarctic station project

Signed-off-by: Jérôme Coupé <jercoupe@gmail.com>