Updated berkshelf to 3.1.5

Updated berkshelf from 2.0.18 to 3.1.5 in Gemfile and added supermarket source to Berksfile

Change-Id: I33b16c3aca1e0864d98a17a8bc8d9213a5aa034b
Implements: blueprint update-berkshelf
Merge "Updated berkshelf to 3.1.5"