Official list of browsers supported

[jdaudier]

@peterblazejewicz @samccone
Can I get an official list of browsers we wanna support for the www, so I can note it for myself when I'm building stuff and to add it to the README?

[peterblazejewicz]

@jdaudier we define support via tools:

• autuprefixer task uses 2 last browser:
  '''
  browsers: ['last 2 version']
  '''
• we use SVGs, including SVG maps

We do not use flex box, so I'd say all modern browsers down to IE9, with note about prefixed vendors properties.

[jdaudier]

OK I will add this to readme:

Last 2 versions of chrome, safari, Firefox, IE9 and up.

Along with your notes above