Certs and context (eclipse-volttron#112)

* Corrected format string in context.py.get_fq_identity().

* Integrates service loader into modular framework.
Updated known identities for services to be volttron.platform.service_name
Added ServerConfig object.

* update identities.

* Updated certs.py to version from 8.2.

* Fix client context so it will load main platform config properly.

Co-authored-by: C. Allwardt <[email protected]>