AppNexus: Add methods for creating/deleting creative templates and retrieving media subtypes
 * Add methods to IAppNexusApiClient and AppNexusApiClient
 * Streamline object tracking/cleanup in AppNexusClientHelper
 * Add stub for traveltorial creative export to AppNexusCreativeExporter
AppNexus: Flesh out traveltorial creative export
 * "Works" end-to-end now
 * Need to add click trackers and CDN content uploading
Utilities: Add CDN Client interfaces, factory, Azure blob implementation and RuntimeIoc registration
Utilities: Add cache host to CloudBlobCdnClient
 * Enables replacing Azure storage URIs with edge caching hosts
AppNexus: Add creative type definitions
Merge branch 'master' into RC131
CDN: Add ICdnClient.Exists(resourcePath) method
 * Used to check if a resource already exists on the CDN
 * resourcePath is the path within the CDN, not a URI
AppNexus: Traveltorial creative exporter

TODO:
 * Add RuntimeIoc registered exporter factories
   - Needed to fix encapsulation break from directly referencing CloudBlobCdnClient
 * Need solution for creative click trackers needing line-item and publisher ids
   - Use dummies w/ useful codes for joining reports?
 * Add ICdnClient.Exists overload with out param for URI if exists
 * Add AzureBlobCdn settings to cscfg/csdef
   - Must add AzureCdnConnectionString and AzureCdnCacheHost to EnvironmentSettings
Merge branch 'master' of https://github.com/RareCrowds/OpenAdStack into RC131
Traveltorial: Work-in-progress
 * Functional except for click trackers
 * Click trackers must be manually created and tokens replaced in exported creative content via AppNexus console after export (will trigger re-audit)
Traveltorial: Get AdTypeDefinitions from company entity
 * Move AdTypeDefinition and CdnMapping to DeliveryNetworkUtilities
 * Add CompanyEntity extension for getting deserialized AdTypeDefinitions

TODO: Add mock/test ICdnClient implementation