* Delete format_tap.py

This python implementation of a tap formatting library for buildkite has been
replaced with a perl implementation as part of the matrix-org/sytest repo,
which is specific to sytest's language, not that of any one homeserver's.

This also adds a worker blacklist.

* Add a sytest blacklist file

* Add changelog

* Add blacklist to manifest

Including workers!

* remove 2.7 from CI and publishing

* fill out classifiers and also make it not be installed on 3.5

* some minor bumps so that the old deps work on python 3.5

Sometimes the build agents get lost or die (error codes -1 and 2). Retry automatically a maximum of 2 times if this happens.

Error code reference:

* -1: Agent was lost
* 0: Build successful
* 1: There was an error in your code
* 2: The build stopped abruptly
* 255: The build was cancelled

* Regen sample config before kicking off agents

* Add changelog