title: enum data type for liquibase
body: <p>I'm currently working on a liquibase.xml file to create table table_a. One of my fields is <code>&lt;column name="state" type="ENUM('yes','no')"&gt;</code>
  I'm using postgresql as my DBMS. is there anything like enum data type? 
  I've read in this like <a href="http://wiki.postgresql.org/wiki/Enum" rel="noreferrer">http://wiki.postgresql.org/wiki/Enum</a></p>
  
  <p>that postgresql doesn't have such data type. CREATE TYPE function is used to create this data type. I still don't know how to make it in liquibase though.</p>
  
  <p>Any suggestions? </p>