Release 0.4.4 (2017-02-01)

Baseline: 4bf8cc30

Cherry picks:
   + ef1c6fd3: msvc_tools.py.tpl: Change default runtime library to
              static

Incompatible changes:

  - Only targets with public visibility can be bound to something in
    //external: .
  - The deprecated -x startup option has been removed.
  - docker_build: change the repository names embedded by
    docker_build. You can revert to the old behavior by setting
    legacy_repository_naming=True.
  - The string methods strip(), lstrip(), and rstrip() now
    by default remove the same whitespace characters as Python 3
    does, and accept
    None as an argument.
  - Deprecated globals HOST_CFG and DATA_CFG are removed. Use strings
    "host" and "data" instead.
  - repository_ctx environment is now affected by --action_env flag
    (value from the
    client environment will be replaced by value given on the command
    line through --action_env).
  - All executable labels must also have a cfg parameter specified.
  - Removed the cmd_helper.template function.
      The function was equivalent to:
        def template(items, template):
          return [template.format(path = i.path, short_path =
    i.short_path)
                    for i in items]
  - Tuples that end with a trailing comma must now be inside parens,
      e.g. (1,) instead of 1,
  - The traversal orders for depsets have been renamed. The old names
    are deprecated and will be removed in the future. New names:
    "stable" -> "default", "compile" -> "postorder", "link" ->
    "topological", "naive_link" -> "preorder".

New features:

  - Skylark: you can now multiply a list by an integer to get the
    concatenation of N copies of this list, e.g. [a,b] * 3 =
    [a,b,a,b,a,b]
  - Allow Android aidl tool to add a jar to the program's classpath,
    such as if needed to support generated sources.
  - Add transitive proguard_specs when android_sdk.aidl_lib is
    specified
  - Windows: "/dev/null" is now a supported path, e.g.
    --bazelrc=/dev/null now works

Important changes:

  - Bazel Android builds use the apksigner tool from the Android SDK
    build-tools. Bazel Android builds now require build-tools version
    24.0.3 or
    later.
  - Android SDK external bindings for support libraries, e.g.
    //external:android/appcompat_v4, are removed because the support
    library JARs that they referenced no longer ship with the Android
    SDK.
  - aar_import rule is now documented.
  - An IE bug was fixed in repository_ctx.download_and_extract
  - Update "-I" to "-isystem" in documentation to reflect current
    behavior.
  - android_sdk_repository build_tools_version is now optional. The
    highest installed build-tools will be used if none is specified.
  - New flag --sandbox_add_mount_pair to specify customized
    source:target path pairs to bind mount inside the sandbox.
  - expose proto_library descriptor set to skylark via
    <dep>.proto.descriptor_set
  - The `set` constructor is deprecated in favor of `depset`
  - Autodetect gold linker in cc_configure.bzl
  - Remove build flag --experimental_j2objc_annotation_processing. It
    is on by default now.
  - Set clang's -mwatchos-version-min correctly using the value of
    --watchos_minimum_os, not --watchos_sdk_version.
  - singlejar can now create jar files larger than 4GB.
  - android_sdk_repository and android_ndk_repository now read
    $ANDROID_HOME and $ANDROID_NDK_HOME if the path attribute is not
    set.
  - Removed broken api levels 3, 4 and 5 from Android NDK 12.
  - Default --android_dynamic_mode to off.
  - android_sdk_repository no longer requires api_level. If one is
    not specified, the highest android platform installed will be
    used. Furthermore, android_sdk's are created for all android
    platforms installed and can be specified with the --android_sdk
    flag.
  - To iterate over or test for membership in a set, prefer using the
    new to_list() method. E.g., "for x in myset.to_list():", or
    "print(x in myset.to_list())". Iteration/membership-test on the
    raw set itself is deprecated.
  - Remove support for --javawarn; use e.g. --javacopt=-Xlint:all
    instead