Added Meta Model slides, including first use case (Large Company)
new file:   docs/Threat Meta Model - Benefits and Use Cases-20140203.pptx

Added Initial Models for STIX
new file:   models/STIX-NIEM-UML.mdzip
new file:   models/STIX-XSD-UML1.mdzip
new file:   models/STIX-XSD-UML2.mdzip