Cache MediaServicesEndpoint using azureMediaServicesEndpoint parameter of AzureMediaServicesClassFactory constructor as the key.
Check cache for null before disposing.
Merge branch 'dev' of https://github.com/WindowsAzure/azure-sdk-for-media-services into dev
Merge pull request #60 from ivan-shaporov/dev

Cache MediaServicesEndpoint using azureMediaServicesEndpoint parameter of AzureMediaServicesClassFactory constructor as the key.