feat(dpd.js) add promises to client library

add ayepromise library dpd.js
client ajax functions return promises

ref #350
test(dpd.js) add client promise tests
Merge pull request #374 from andyzickler/client-promises

feat(dpd.js) Add promise support to dpd.js
Merge pull request #1 from deployd/master

changes from upstream
Merge pull request #2 from pollion/master

merge from upstream