Add title to job chains

Job chains shall have a title:

1) Configuration

<job_chain name="my_chain" title="My Chain">...</job_chain>

Job chain configurations in XML files or hot folders support the attribute title=

2) XML Answers

XML answers from Job Scheduler that return job chains shall return the attribute title=

3) API

• Set the title:
  my_job_chain.title = "My Chain"

• Read the title
  echo my_job_chain.title