XD-1014 + XD-1013 Show XML Config File Contents

* XD-1013 Add additional REST endpoint that return the XML definition of a job
* XD-1014 Command to show the XML of the job definition

Question to the reviewer: 

**1)** 

Currently the rest-url is:

`/modules/{type}/{name} (MediaType.TEXT_PLAIN_VALUE)`

Should this rather be `/modules/{name}` with **type** being a RequestParam instead? That way we could make the type parameter optional, **PROVIDED** that only ONE definition exists across all types.

**2)** 

Should we create a Jira to return the Meta-information for a specific definition?

/modules/{type}/{name} (MediaType.APPLICATION_JSON)

E.g. providing information on the file location of the definition etc.). That way we would provide slightly more information in the command-shell when executing `module display --name myname --mytype`.

Jiras:

* https://jira.springsource.org/browse/XD-1013
* https://jira.springsource.org/browse/XD-1014