Python3: fix bytes/str issues

In Python 3, tempfile.NamedTemporaryFile().write() takes bytes as input,
not a text string. Make sure we use bytes in the tests. Also, completely
fix test_get_template_contents_file by passing a string to
template_utils.get_template_contents().

Change-Id: I49070b32e44a405740e3150ccc357ec375f41e64
Support the native signal API

The patch adds a new command to send a signal to a resource.

Change-Id: Ic0d7390e31114e1a58b700c57b838c059bf5b086
Merge "Support the native signal API"
Merge "Python3: fix bytes/str issues"