added sender_addr to permitted params
moved to controller (seems to belong here?!)
closes #4
closes #3

+ added helper method for recent wallet address or label
+ cleaned up transaction new form
logo added
improved layout, styling and D.R.Y. regarding partials
set page_title everywhere; closes #6
added array cluster extension
sender_addr validation added
added transaction helper for grouping transactions
catch exception if label is too long
added qrcode to show wallet
added grouping by wallet and status
use receiverqrcode_params