This commit adds the utils module to those for which Sphinx
automatically generates documentation from docstrings. (Many of the
functions here may be of little interest to users, but
`generate_temp_url`, at least, definitely deserves to be in the
documentation; in this way, this commit can be seen as a spiritual
companion to ca70dd9e.)
Also, a few markup errors and perceived infelicities in existing
docstrings are amended.
Change-Id: I8c66a23cb359d7dd9302a16459fad9825fedb690