Restore json dependency to 1.8.1
Restore json dependency to 1.8.1

Set dependncy back to JSON 1.8.1 ais required for Ruby 1.9.3 support

Signed-off-by: Adam King <a74e182e49abf6252c9b13e1b94c4c5a47f8da9a@us.ibm.com>

travis-ci/dpl,pengsrc/dpl,testfairy/dpl,testfairy/dpl,travis-ci/dpl,travis-ci/dpl,testfairy/dpl,computology/dpl