Merge pull request #742 from Polymer/update-bower-sinon

Change version of sinonjs to Polymer/sinon.js instead of blittle/sinon.js

5.0.2

4.3.7

6.6.0-pre.5

6.6.0-pre.4

6.6.0-pre.3

6.6.0-pre.2

6.6.0-pre.1

6.5.0

6.4.3