Fixing bash helpers vars test

Summary:
Fixing test app file_load/vars, to properly check for array equivalence. This ensures
correctness of the bash helper variables.

Test Plan: Fixing a test.

Reviewers: klai

Differential Revision: https://phabricator.dnanexus.com/D150
Merge branch 'improving-bash-vars-test' of github.com:dnanexus/dx-toolkit into improving-bash-vars-test