better offline handling

[frankiebee]

better offline handling related too #2548

at this moment it's hard to use metamask when your offline...
some things that would be nice to have:
getting your pub. key while offline maybe you just want you friend to scan your qrcode or something on their phone but you dont want to go through all the trouble of connecting to the wifi
danger signing transactions offline (relying only on local nonce and not the network nonce)
ect.

[frankiebee]

• dont block on loading indicator
• throttle polling on slow internet
• allow offline sign
• dont poll unseen account balances

[frankiebee]

• "gray out"/disable features that require network connection along with a little info that they are offline

[frankiebee]

note: throttling polling seems less important on the wifi and needs more thinking before execution(and may be a fixing something that isnt broken)
I think the better use of time is "danger" signing offline transaction as this would also be a feature that some people who have spoken with me in the past have asked about.

[bdresser]

Closing due to inactivity - if this is still relevant, feel free to open a new issue.