Rename BUILD to BUILD.bazel.

This avoids conflicts with build/ on case-insensitive filesystems.

Fixes #606.
diff --git a/BUILD b/BUILD.bazel
similarity index 100%
rename from BUILD
rename to BUILD.bazel
diff --git a/bazel/example/BUILD b/bazel/example/BUILD.bazel
similarity index 100%
rename from bazel/example/BUILD
rename to bazel/example/BUILD.bazel
diff --git a/bazel/glog.bzl b/bazel/glog.bzl
index 495ea63..ba19dcd 100644
--- a/bazel/glog.bzl
+++ b/bazel/glog.bzl
@@ -1,4 +1,4 @@
-# Implement a macro glog_library() that the BUILD file can load.
+# Implement a macro glog_library() that the BUILD.bazel file can load.
 
 # By default, glog is built with gflags support.  You can change this behavior
 # by using glog_library(with_gflags=0)