replace s4agri namespace for:
sosa:Platform, ssn:System, ssn:Deployment and related properties

update URI to SAREF for: FeatureOfInterest, isPropertyOf, hasProperty,
hasFeatureOfInterest, isFeatureOfInterestOf and measurementMadeBy

update URI to SAREF for: FeatureOfInterest, isPropertyOf, hasProperty,
hasFeatureOfInterest, isFeatureOfInterestOf and measurementMadeBy

Added comments for all entities.

Some links to SSN/SOSA have been indicated.

Added labels and comments.
Added deployment time and spatial relations.
Changed saref:consistOf property for the networks componency for the
Constituency pattern relationships.

Added readme for SAREF4AGRI

Include main classes and properties  in the diagram for the “Use case
2: Smart irrigation”.

Include main classes and properties for the “Use case 2: Smart
irrigation”.

added diagram and owl code for s4agri first working draft