foursquare/fongo — pull request #11 by tobyclemson (2012-12-17 18:47:57+00:00)
Title: Allow Map instances to be passed in query objects since this is permitted in the Java driver.

The Java Driver supports a query object of the following form:

```java
HashMap operatorMap = new HashMap();
operatorMap.put("$in", asList(1, 2, 3));
BasicDBObject query = new BasicDBObject("a", operatorMap);
```

with a value that is a ```Map``` containing further expressions and operators.

It is important to me that this is supported since this behaviour is leveraged by morphia when creating queries.

This pull request extends ```ExpressionParser ``` to allow this case and adds a test to demonstrate usage.