terminal-notifier: Only supports 10.8

I think notification center is not availabe on 10.7 or older.

Added a caveat that without code sign, terminal-notifier
will not be able to open URLs or apps.

Fixed audit about SYMROOT.
terminal-notifier: Style bits.
selenium-server-standalone: 2.33

Closes #20242.

Signed-off-by: Samuel John <github@SamuelJohn.de>
terminal-notifier: test seems to hang on brew-test-bot
boost: don't use bottle if python brew installed.

Closes #20124.
Don't error out on unreleased OSX versions.

References #20142.