added RHKeychain

RHKeychain should allow to store the wallet into the Mac OSX Keychain

Signed-off-by: Jonas Schnelli <jonas.schnelli@include7.ch>
prepared XIB for some wallet functions

Signed-off-by: Jonas Schnelli <jonas.schnelli@include7.ch>
big "sendcoins" overhaul

Signed-off-by: Jonas Schnelli <jonas.schnelli@include7.ch>