(PUP-1246) Fixed hiding error details in fileserver.conf parser

This patch fixes wrong parser behavior in case when fileserver.conf
contains some broken lines. It helps to debug configuration problems
and makes puppet's user life a little bit easier.

Also added 2 unit tests for validating these buggy cases.
(PUP-1246) Update tests to show line numbers

The previous tests didn't check that the correct line number was being
reported. This updates the checks so that we can verify the line number.
Merge branch 'drednout-master'

* drednout-master:
  (PUP-1246) Update tests to show line numbers
  (PUP-1246) Fixed hiding error details in fileserver.conf parser

Closes GH-2185