(MODULES-1190) respect puppet-lint ignore paths in Rakefile

Without this patch applied, the PuppetLint.configuration.ignore_paths
specified in the Rakefile is discarded in favour of the hardcoded value
provided by puppetlabs_spec_helper from v0.5.0.  This patch fixes the issue
by adding the hardcoded value to the array rather than overwriting it.
MODULES-1202 - add module_spec_helper support for config items stringify_facts, trusted_node_data and ordering
MODULES-1202 clarify upstream PR in comment
Merge pull request #70 from jantman/MODULES-1202

MODULES-1202 - add module_spec_helper support for 3.6 config items
Merge pull request #69 from mmickan/fix/master/MODULES-1190

(MODULES-1190) respect puppet-lint ignore paths in Rakefile