Changes to SQL Geo-Restore commandlets

With MAML package 2.0.0 the API for getting recoverable databases and for creating database recovery operations has changed. This updates the Get-AzureSqlRecoverableDatabase and Start-AzureSqlDatabaseRecovery commandlets for the same.

Summary of changes:


Get-AzureSqlRecoverableDatabase
- A single -ServerName parameter instead of -SourceServerName and -TargetServerName
- -SourceDatabaseName parameter is now called just -DatabaseName
- -SourceDatabase parameter is now called just -Database and changed type from ```Microsoft.WindowsAzure.Commands.SqlDatabase.Services.Server.RecoverableDatabase``` to ```Microsoft.WindowsAzure.Management.Sql.Models.RecoverableDatabase```
- Return type changed from ```Microsoft.WindowsAzure.Commands.SqlDatabase.Services.Server.RecoverableDatabase``` to ```Microsoft.WindowsAzure.Management.Sql.Models.RecoverableDatabase```


Start-AzureSqlDatabaseRecovery
- -SourceDatabase parameter changed type from ```Microsoft.WindowsAzure.Commands.SqlDatabase.Services.Server.RecoverableDatabase``` to ```Microsoft.WindowsAzure.Management.Sql.Models.RecoverableDatabase```
- Return type changed from ```Microsoft.WindowsAzure.Commands.SqlDatabase.Services.Server.RecoverDatabaseOperation``` to ```Microsoft.WindowsAzure.Management.Sql.Models.RecoverDatabaseOperation```


This is pending release of 2.0.0 version of the Microsoft.WindowsAzure.Management.Sql package ( https://github.com/Azure/azure-sdk-for-net/pull/757 )