make static html versions of jenkins reports for archiving

Too many archived builds slows jenkins down (as it reads all of the xml files from disk, parses them, and keeps them in memory). Web servers are fast. So let's generate static versions of the important jenkins reports and logs, and archive them onto a web server, and tell Jenkins to keep fewer jobs in the build history. This will entail:

* Writing a script to generate a static HTML report from nosetests.xml.
* Finding a way (maybe another script) to get the console log as a file. Preferably with timestamps.
* Switching the coverage jobs to just produce HTML natively.
* Uploading these and any other logs (like devstack logs) to a web server.

The files can be uploaded to a predictable directory, such as "/job-name/job-number/" and then Zuul can be reconfigured to link directly to that URL instead of Jenkins.