Implements Set-AzureEnvironment cmdlet
Apply code review
Fix startup script path
Throw exception when environment already exists
Merge pull request #1610 from ogail/1601

Implements Set-AzureEnvironment cmdlet
Remove validation for publish settings file
Add StorageEndpoint to Add-AzureEnvironment parameter
Fix parameter sets
Make loading global components lazy.
Add DNS validation
Merge pull request #1618 from ogail/1617

Add StorageEndpoint to Add-AzureEnvironment parameter
Merge branch 'dev' of https://github.com/WindowsAzure/azure-sdk-tools into dev
Merge branch 'dev' of https://github.com/AzureRT/azure-sdk-tools into dev