Allow raw properties to be inserted into iOS/Android push messages

When adding event properties to a template, they have to be wrapped as a string value. Trying to insert an event property as it's raw data type results in a parsing error. In our use case, we want to include the badge count in a notification payload. Apples APNS expects the data type to be an integer, so sending it as a string doesn't work, but adding the property not wrapped as a string results in a parsing error. This can be seen in the attached screenshot. After speaking with Vero support escaping the curly brackets isn't an option.