Obsolete references to Google Code

[jwilk]

Google Code was shut down in 2016, but there are still references to the old location in the ruffus code:

$ git grep -F code.google.com/p/ruffus
doc/_templates/index.html:The very latest (in development) code can be obtained via <a href="https://code.google.com/p/ruffus/source/checkout"> git </a>:
doc/_templates/index.html:   <pre>git clone https://[email protected]/p/ruffus/</pre>
doc/_templates/index.html:        href="http://code.google.com/p/ruffus">Google 
doc/_templates/index.html:    <a href="http://code.google.com/p/ruffus/issues/list">Bugs or feature requests can be posted here.</a>
doc/examples/bioinformatics/index.rst:    Otherwise, `download <http://code.google.com/p/ruffus/downloads/list>`_ Ruffus and run:
doc/installation.rst:            git clone https://[email protected]/p/ruffus/ .