xcode: use 6.1 on Mavericks.

Closes #33399.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
doctor: Xcode 6.1 is in the App Store.
libharu: add 2.2.1_1 bottle.
libical: update 1.0 bottle.
libiptcdata: update 1.0.4 bottle.
libiscsi: update 1.10.0 bottle.
brew-test-bot: be more resilient to bad arguments.
libbs2b: update 3.1.0 bottle.
libbtbb: update 2014-02-R2 bottle.
libcapn: update 1.0.0b3 bottle.
libcddb: update 1.3.2 bottle.
libcec: update 2.1.4 bottle.
libcello: update 1.1.7 bottle.
libcoap: update 4.1.1 bottle.
libcouchbase: update 2.4.2 bottle.
libcsv: update 3.0.3 bottle.
libdap: update 3.12.1 bottle.
libdc1394: update 2.2.2 bottle.
libdca: add 0.0.5 bottle.
libdrawtext: update 0.1 bottle.