bumped build target to 17
allow options menu items into action bar
reduced donation suggestion to millibitcoins
added dialog to help potential donors without wallets

previously, if a user with no program to handle a bitcoin: Intent clicked the
donation link they'd FC for an unhandled Intent.  Now a helpful dialog pops up
and gives options to copy the address, get the QR from blockchain.info or
install the Schidbach wallet on their device.
suppress background gradient when using holo theme
bumped version info to 2.1