message: Update MOBILE API to version 6.0.0
diff: <?xml version="1.0" standalone="no"?>
  <?xml-stylesheet type="text/xml" href="protocol2html.xsl"?>
  -<interface name="SmartDeviceLink RAPI" version="5.2.0" minVersion="1.0" date="2019-03-19">
  +<interface name="SmartDeviceLink RAPI" version="6.0.0" minVersion="1.0" date="2019-03-19">
  <enum name="Result" internal_scope="base" since="1.0">
  <element name="SUCCESS">
  <description>The request succeeded</description>
  Audiobook: The total number of sections in the playback queue (e.g. the number of chapters in the book)
  </description>
  </param>
  - <param name="mediaImage" type="Image" mandatory="false" since="5.2">
  + <param name="mediaImage" type="Image" mandatory="false" since="6.0">
  <description>
  Music: The album art of the current track
  Podcast: The podcast or chapter artwork of the current podcast episode
  