title: json_each and json_each_text results with different column names
body: <p>I've just upgraded to <em>Postgresql 9.3beta</em>. When I apply <strong>json_each</strong> or <strong>json_each_text</strong> functions to a json column, the result is a set of rows with column names <strong>'key'</strong> and <strong>'value'</strong>.</p>
  
  <p>Here's an example:</p>
  
  <p>I have a table named <code>customers</code> and <code>education</code> column is of type <code>json</code></p>
  
  <p>Customers table is as follows:</p>
  
  <pre><code> ----------------------------------------------------------------------
  | id | first_name | last_name | education                              |
   ---- ------------ ----------- ----------------------------------------
  | 1  | Harold     | Finch     | {\"school\":\"KSU\",\"state\":\"KS\"}  |
   ----------------------------------------------------------------------
  | 2  | John       | Reese     | {\"school\":\"NYSU\",\"state\":\"NY\"} |
   ----------------------------------------------------------------------
  </code></pre>
  
  <p>The query</p>
  
  <pre><code>select * from customers, json_each_text(customers.education) where value = 'NYSU'
  </code></pre>
  
  <p>returns a set of rows with the following column names</p>
  
  <pre><code> ---------------------------------------------------------------------------------------
  | id | first_name | last_name | education                              | key    | value |
   ---- ------------ ----------- ---------------------------------------- -------- -------
  | 2  | John       | Reese     | {\"school\":\"NYSU\",\"state\":\"NY\"} | school | NYSU  |
   ---------------------------------------------------------------------------------------
  </code></pre>
  
  <p>because <code>json_each_text</code> function returns the set of rows with <code>key</code> and <code>value</code> column names by default.</p>
  
  <p>However, I want <code>json_each_text</code> to return custom column names such as <code>key1</code> and <code>key2</code>:</p>
  
  <pre><code> -----------------------------------------------------------------------------------------
  | id | first_name | last_name | education                              | key1    | value1 |
   ---- ------------ ----------- ---------------------------------------- -------- ---------
  | 2  | John       | Reese     | {\"school\":\"NYSU\",\"state\":\"NY\"} | school  | NYSU   |
   -----------------------------------------------------------------------------------------
  </code></pre>
  
  <p>Is there a way to get different column names like <strong>'key1'</strong> and <strong>'value1'</strong> after applying those functions?</p>