bower: allow using latest bugfix release
bower: allow using latest bugfix release

We will keep doing manual feature jumps for now. We may be able to
change this to '^x.y' in the future to say we want any version
compatible with version x.y.

mgeisler/swift-browser,mindware/swift-browser,mindware/swift-browser,zerovm/swift-browser,mgeisler/swift-browser,zerovm/swift-browser