Run puppet facts find test on master only

Previously we were populating the puppetdb using 'apply' but only on the
master, our tests however were expecting to find results on all hosts which
caused a JSON parse exception.

This patch just changes that test to only test `puppet facts find` on the
master.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #523 from kbarber/fix_test_json_parse_error

Run puppet facts find test on master only