use Oozie delegation token, if provided

The oozie shell-action script which invokes "slider create" must dynamically create a token.conf file, as follows:

echo "&lt;configuration&gt;&lt;property&gt;&lt;name&gt;mapreduce.job.credentials.binary&lt;/name&gt;&lt;value&gt;${HADOOP_TOKEN_FILE_LOCATION}&lt;/value&gt;&lt;/property&gt;&lt;/configuration&gt;" &gt; token.conf

Then, the script invokes "slider create -conf token.conf" with the included changes.