utils: return empty issues array when no API.
python_dependency: always bottle with brew Python.
boost: use new python requirement bottle logic.
keg: add delete_pyc_files! method.
bottle: remove pyc files before bottling.

Allows more `cellar :any` bottles.
pkg-config: restore bottle.
brew-test-bot: hide --retry flag.
brew-test-bot: use install_args for building deps.
boost: add Xcode 5.1 patch for boost::atomic.

Needed for LLVM 3.4.
boost: update 1.55.0 bottle.

Closes #27436.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
libqglviewer 2.5.1
libqglviewer: add 2.5.1 bottle.

Closes #27501.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
libqglviewer: remove caveat recommending sudo.
swig: add 2.0.12 bottle.
python3: add 3.3.5 bottle.
libxml2: add 2.9.1 bottle.
python: add 2.7.6 bottle.