Armory offline

Submitting  this PR to get some feedback on the flow and UI, so far it has been tested for bitcoin send only.

DEx transactions (buy/sell) are not supported right now because they implement a different architecture on the front end.

The steps for testing are described here: https://github.com/mastercoin-MSC/omniwallet/wiki/Armory-Offline-Addresses

Smart Property creation should work in the same manner.