VERSION 0.6.2: Mac users should 'sudo make install-mac-tap' again.

This version fixes a recurrent gremlin in the tap driver for Mac. If you are
having this issue, you should reinstall the tap.

If you're already running ZT1, shut it down (sudo killall zerotier-one) and
then do:

sudo kextunload /Library/Application\ Support/ZeroTier/One/tap.kext

This should unload the old version. Then type 'sudo make install-mac-tap' in
the ZT1 source home directory and the new version will be installed. ZT1 will
load the module again when it next starts.

In addition to a fix, I am now distributing tap binaries and it is no longer
built in the default Makefile. This is because Apple's in the midst of some
changes that have made building it somewhat difficult.

Another note for Mavericks users:

The first time you use ZT1, you will get a popup about unsigned kernel
extensions. This will vanish once we're out of beta and have signing keys
and signed drivers.

Other changes in this version:

 * Minor improvement to Utils::getSecureRandom
 * Bug fixes and a small change to certificates of membership for private
   networks, which now appear to be working very well!
 * Stubbed out messages for auto-update, which will be done in-band via
   the ZT1 protocol. Not implemented yet.