title: Mongoid: select embedded objects that fits number of options
body: <p>I have got this structure</p>
  
  <pre><code>class House
    include Mongoid::Document
    embeds_many :inhabitants
  end
  
  class Inhabitant
    include Mongoid::Document
    embedded_in :house
    field :name
    field :gender
    field :age
  end
  </code></pre>
  
  <p>I can get all houses where females live:</p>
  
  <pre><code>houses = House.where("inhabitants.gender" =&gt; "female")
  </code></pre>
  
  <p>But how can I get all houses where females under age 50 live? How can I specify more than one condition for embedded object?</p>