This makes it easy to store UNIX sockets with correct permissions. Those
would be located in /run/synapse which is the directory used in many
examples in Synapse configuration manual. Additionally, the directory
and sockets are deleted when Synapse is shut down.

* Remove unused Vagrant scripts

* Change package Architecture to any

* Preinstall the wheel package when building venvs.

Addresses the following warnings during Debian builds:

    Using legacy 'setup.py install' for jaeger-client, since package 'wheel' is not installed.
    Using legacy 'setup.py install' for matrix-synapse-ldap3, since package 'wheel' is not installed.
    Using legacy 'setup.py install' for opentracing, since package 'wheel' is not installed.
    Using legacy 'setup.py install' for psycopg2, since package 'wheel' is not installed.
    Using legacy 'setup.py install' for systemd-python, since package 'wheel' is not installed.
    Using legacy 'setup.py install' for pympler, since package 'wheel' is not installed.
    Using legacy 'setup.py install' for threadloop, since package 'wheel' is not installed.
    Using legacy 'setup.py install' for thrift, since package 'wheel' is not installed.

* Allow /etc/default/matrix-synapse to be missing

Per the systemd.exec manpage, prefixing an EnvironmentFile with "-":

> indicates that if the file does not exist, it will not be read and no
> error or warning message is logged.

Signed-off-by: Dan Callahan <danc@element.io>

It should be possible to reload `synapse.target` to have the reload propagate
to all the synapse units.

Simplify and update this documentation, and make it part of the core dist.