Utilities/Release: Fix name of OS X 10.6+ x86_64-only binary

In commit v3.1.0-rc1~52^2 (Make the OSX 10.6+ release x86_64 only,
2014-09-29) we forgot to remove the name "universal" from the binary
name.  Since the binary is no longer universal, use "x86_64" instead.

While at it, update the deployment target to actually be 10.6.
Utilities/Release: Build Windows and OS X binaries with native SSL

For the nightly binaries, turn of CMAKE_USE_OPENSSL on Windows and OS X
10.6+ platforms.  This will activate the new curl behavior to use the
OS-native SSL/TLS implementation.
Merge topic 'nightly-binary-updates' into next

202056cd Utilities/Release: Build Windows and OS X binaries with native SSL
d64caa53 Utilities/Release: Fix name of OS X 10.6+ x86_64-only binary