brew-test-bot: check default_formula requirements.

This handles the case where e.g. a default_formula cannot be installed
on Yosemite which causes the build to fail.
jmeter 2.12

Closes #34283.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
syncthing 0.10.6

Closes #34287.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
syncthing: update 0.10.6 bottle.
jmeter 2.1.2, update plugins, use apache archive as source

the old dyn/closer.cgi url fails to serve old versions