add Coinbase as a mobile wallet

[jonnycsolo]

Adding Coinbase's mobile offerings

I added Coinbase as a mobile wallet, since it has an official Android app and an officially-endorsed iOS app.

Appropriately-sized screen shots of the iOS and Android app have been included.

I also updated English (_translations/en.yml) and French (_translations/fr.yml) language files to reflect the availability of the iOS app.

[saivann]

@jonnycsolo Thanks for submitting a pull request but as you might have noticed, all wallets that don't provide the user with control over their private keys are only listed under the "Web" category. There is many reasons for this, the main one being that these wallets are controversial due to their very bad track record (security and systemic risk).

It's also unclear if listing them alongside other wallets is somewhat misleading, since they're more similar to banks and online banking in general than a "wallet". This is the kind of difference bitcoin.org should help people to understand.

[saivann]

Closing the issue for inactivity.