Update test framework to work with newest volttron 3 code base

[x] Make sure that there is a way to write unit tests for code under the volttron.platform package as well as the different agents.
[x] Move tests from volttron.tests to an external package
[x] Create a package for using within agent tests to wrap the platform itself. (use what is already there if not too broken.)
[x] cleaning the temporary directory is not happening currently. This needs to be fixed (as a work around right now use

rm -rf /tmp/*
sudo killall -9 volttron 
sudo killall -9 python

VOLTTRON / volttron