store Common Information Model name in ulogd key

store Common Information Model name in ulogd key

This patch adds storage for CIM field name in ulogd key. This
will be used by JSON output to interoperate with logging
collector such as logstash or splunk.

Common Information Model is an open standard that defines how managed
elements in an IT environment are represented as a common set of objects
and relationships between them:
 http://www.dmtf.org/standards/cim

This seems to be mainly XML based but there is a JSON version of some
aspects of the model. One of the main documentation on CIM in JSON
format seems to be:
 http://docs.splunk.com/Documentation/PCI/2.0/DataSource/CommonInformationModelFieldReference

Using the correct CIM field name allow events coming from ulogd to be
correlated with events coming from other sources.