Can't use variable to specify dependsOn

If you put an array of strings into a variable, and then try to use that variable for dependsOn you get an error stating it can't convert the value to a System.String[]

```
New-AzureRmResourceGroupDeployment : 12:02:37 AM - Error: Code=InvalidRequestContent; Message=The request
content was invalid and could not be deserialized: 'Error converting value "[variables('dependsOnVar')]" to
type 'System.String[]'. Path 'properties.template.resources[1].dependsOn', line 68, position 53.'.
```

Start by reproducing the Azure Resource Group deployment described in the issue with an array-valued variable used for dependsOn. Check how the deployment template serializes that expression and verify completion by confirming the template is accepted without the System.String[] deserialization error.

Written by the indexing model from the issue text.