If .ninja_log contains an entry that used to be a file but is now a
non-empty directory the os.Remove call will fail. Silently ignore
this error, if the files in the directory are abandoned the directory
will be cleaned up when the files are removed.
Make integrating with go tools easier by putting the blueprint package
files in the top level directory of the git project instead of in a
subdirectory called blueprint.
Change-Id: I35c144c5fe7ddf34e478d0c47c50b2f6c92c2a03
