Adding server key and cert files to installation

This change adds the server key and cert file from kmip/demos/certs to
the MANIFEST.in and setup.py files. These files are being added to
resolve missing file issues when using the default cert values.

Changes
* adding server.crt and server.key to MANIFEST.in and setup.py
* correcting mismatched default values for KMIPServer certfile and
  keyfile