This commit removes .testr.conf since this repo already has
.stestr.conf. We just need .stestr.conf instead of .testr.conf.
Change-Id: I22570efeec854d4b26ce10c6820a96349c1b625a
Following commits does several things:
* migrates CI of monasca-common to ostestr
* enables PY35 compatybility
Also:
* marked one tests as excluded under PY35 because changing
it would require affecting embedded kafka library which
will be eventually removed in future
Change-Id: I432a466e2620bc8d305ef2630307b636461c8e81