Device model from sources

[wsobel]

Added support for dynamic addition or updates to the devices in the agent from sources.

Added the following capabilities:

• Creating unique ids for all entities
• Keeping track of the original ids and serializing them to the Device XML but not to the probe
  • Written to support future configuration attributes if necessary
• Versioning the Device XML file with a timestamp every time it changes
• Still supporting the resolution of original ids from the source on a per-device basis
• Restarts of the agent do not remove the id mapping, it is preserved
• Resolves all relationships between idrefs and relationships
• Initial behavioral tests implemented.
• Added support for multi-line commands in the SHDR interface.
  • now supports deviceModel command as follows:

• deviceModel: --multiline--AAAAA ...

  --multiline--AAAAA

• Needs more testing.