Add test specifying multi-line plain text node output

We want to make sure that multiple plain text nodes aren't coalesced
into a single statement, since our naive method of outputting dummy
`puts` statements wouldn't work with multi-line strings, since it uses a
comment marker which can only span a single line.

Change-Id: If8a05e3162a63e5fc908a089c09bb0218d7e8624
Reviewed-on: http://gerrit.causes.com/45076
Tested-by: jenkins <jenkins@brigade.com>
Reviewed-by: Shane da Silva <shane.dasilva@brigade.com>