title: How to update a customfield in Jira using jira4r
body: <p>I am using jira4r to connect to Jira.  So far I am able to create new RemoteIssues, update existing RemoteIssues (standard fields like summary), but I am not able to update a custom field.</p>
  
  <p>I am able to create a new issue with values in the custom fields, and I am able to read values from custom fields, but I have not been able to update a custom field.</p>
  
  <p>Help appreciated.</p>