title: Setting Date Time Picker Jira field values with jira-python
body: <p>Story: 
  I am using the jira-python api library to create issues in JIRA. I created a custom due date field for my issues (customfield_10300 in code below). This custom field is a Date Time picker. </p>
  
  <p>Problem: The code below tries to creates an issue but returns an error because the syntax for setting the Date Time picker (customfield_10300) value is incorrect. Does anyone know how I would do this?</p>
  
  <pre><code>from jira import JIRA
  jira = JIRA(options,basic_auth=('auth_email','auth_pw'))
  
  issue_dict = {
      'project': {'key': 'AT'}, 
      'summary': 'Update test',
      'description': 'Not important',
      'issuetype': {'name': 'Bug'},
      "customfield_10300" : '10/22/2017  10:00:00 AM', #Problem: Date Time Picker Field, not working
  }
  new_issue = jira.create_issue(fields=issue_dict)
  </code></pre>
  
  <p>P.S. In Jira the field is a "Dates" field, located next to Created and Updated. I assume the syntax for modifying their values would be the same.</p>