Change publish setting file parameter to be mandatory
Update help doc for Import-AzurePublishSettingsFile
Updated SetupEnv.ps1

* Added parameter names for clarity and readability
* Change expression for `$setVSEnv` to use .NET formatting instead of confusing double-quote escaping
* Added message to inform user that AzurePSRoot already exists (if applicable)
Merge pull request #2801 from ljhljh235/manpubfile

Change publish setting file parameter to be mandatory
Merge pull request #2803 from pcgeek86/patch-3

Updated SetupEnv.ps1
Merge branch 'dev' of https://github.com/Azure/azure-sdk-tools into dev