v2016.01.18.01

Release

@mikekap fixed Buck parsing the verbosity from a command running with buck run
buck root was added: https://buckbuild.com/command/root.html
@mogers added the buildfile operator to buck query: https://buckbuild.com/command/query.html#buildfile
@mikekap updated Buck to use the latest version of PEX: https://github.com/pantsbuild/pex/
@davido fixed a number of bugs with cross-cell build targets
@anorth fixed a bug that prevented Buck from running under Python 3.5
@davido fixed a long shutdown time issue when parallel parsing is enabled
python_test now properly handles errors when setting up the test class
Fixed a bug when compiling with clang for NDK builds (assembling would fail)
@grumpyjames added support for groovy_library: https://buckbuild.com/rule/groovy_library.html
Buck can now take an agentpath for the invocation of the ProGuard step. This allows profiling with tools like YourKit and Profiler, which can be useful when trying to determine which optimizations you want to enable for your project. See https://buckbuild.com/concept/buckconfig.html#tools for more details.
buck publish now checks to make sure a library you are publishing doesn't package a library that another library will also package and publish.