Update 20487C_MOD12_DEMO.md
Update 20487C_MOD12_DEMO.md

updating Allfiles path, fixing code formatting issue
MicrosoftLearning/20487-DevelopingWindowsAzureAndWebServices,MicrosoftLearning/20487-DevelopingWindowsAzureAndWebServices,MicrosoftLearning/20487-DevelopingWindowsAzureAndWebServices