New app icons

.icns for Mac have been tested and carries all sizes needed even for
Retina displays.

.ico should work well, but the build process for making Windows builds
is broken for me, so it need to be tested with binaries.

.png replaced witht the latest version
Merge pull request #349 from rdymac/icons

New app icons
remove -b option for listaddresses (fix issue #343)
create a subdirectory for wallets, under default path
move old wallet to subdir