Discourage private keys (pt. 1)

[wbobeirne]

Checks off a few from #557. Implements the warning text from v3, but cranks it up to 11. This was a pretty quick pass at this, so I'm looking for plenty of feedback on how it looks and reads. I call this part 1 since it doesn't hit all checkboxes, and I'd like to see #778 get resolved as a part 2.

What This Does

• Makes users read and confirm warnings before unlocking private keys, keystore files, or mnemonic phrases
• Makes the Account view the default homepage.
• Adds a link to the Generate tab on Account's wallet unlock for if you don't have a wallet.

What This Doesn't Do

• Passwordify private key / mnemonic
• Force user to wait. I felt the checkboxes would be enough of a roadblock.
• Homepagify account. Could use some guidance on what this might look like.

Screenshots

New Homepage

Insecure Unlock Warning

Acknowledging

[wbobeirne]

From Taylor on Slack:

I like it for when we have the apps. let’s circle back in a week after we see what the general feedback on the current changes are from the community
Im curious to know if we’re being “too scary”
finding the balance between educate, scary, etc will be good

I'll leave this PR open while we wait for more feedback about the messaging in v3.

[wbobeirne]

I'm pretty sure we're moving forward on this one. I've merged the latest develop in, and confirmed that it does not bother you on the Electron or HTML download builds.