Update to neubot-server v0.6.0.5

[bassosimone]

This pull request updates to neubot-server v0.6.0.5. The most relevant changes in there is the update to botticelli v0.0.6 that fixes the implementation of the NDT protocol as described in neubot/botticelli#18. All other changes are documentation changes.

Testing

• smoke testing with test machines
• deploy v0.6.0.5-sbs.2 on neubot.mlab.mlab1.trn01 (i.e. the server closest to my home)
• make sure that measurement-kit NDT works with neubot.mlab.mlab1.trn01
• make sure that official NDT with Don't assume server supports all test types ndt-project/ndt#216 works with neubot.mlab.mlab1.trn01
• stress test neubot.mlab.mlab1.trn01.measurement-lab.org with measurement-kit NDT, official NDT, and neubot tests, then
• make sure test results are written on disk and parse as JSON
• make sure rsync and syslog are running on the sliver
• make sure the memory usage of neubot and botticelli is reasonable
• both are running under the expected non privileged user
• the sliver does not appear to be offline as far as data collection is concerned