SqlDatabase: removing unneeded logic from Set-AzureSqlDatabaseServer that caused the cmdlet to no-op if the user didn't pass in the new password on the command line.
SqlCommand: Adding in custom PSHost and PSHostUserInterface files to aid in testing certain scenarios.
SqlCommand: Adding tests and re-generating mocksessions file.
Merge branch 'dev' of https://github.com/Azure/azure-sdk-tools into set-server-password-fix

Conflicts:
	src/ServiceManagement/Sql/Commands.SqlDatabase.Test/Resources/MockSessions.xml
	src/ServiceManagement/Sql/Commands.SqlDatabase.Test/UnitTests/Server/Cmdlet/ServerCmdletTests.cs
Merge pull request #2897 from akromm/set-server-password-fix

Set server password fix