Handle Javascript Disabled

[dternyak]

Right now the site just renders its broken state without Javascript. We should show a message about enabling it.

Likewise, we'll probably want to make a page that tells people to upgrade. We should settle on what features a browser NEEDS to run MEW.

[wbobeirne]

Should be straightforward with a <noscript> tag.

As for required features, I think the only hard requirement is local storage (Which damn near every browser has,) and a soft requirement of flexbox (A lot of messed up layouts otherwise.) But regardless, we should probably have a bottom line somewhere, if only to improve user experience / awareness of superior browsers and the potential security implications.

[dternyak]

@wbobeirne I think this issue ties in with MyEtherWallet/MyEtherWallet#210, in that we need a way to provide messaging to users who are on platforms we do not support.

I'll assign you to #210 as well - let me know if you'd like that re-assigned at any point.

[wbobeirne]

Great, I'll add that to the bad browser check. I have a branch ready to go, just waiting to do some checking once we get browserstack sorted.