update s3 upload task and update Gemfile.lock dependencies

Stops the error of "ember.prod.prod.js" not found on Travis, and also
updates the Gemfile to use the new gzip stuff for uploading to s3.
Merge pull request #3164 from fivetanley/new-s3-config

update s3 upload task and update Gemfile.lock dependencies
make handlebars compilation output repeatable

handlebars compilation when run twice produced different result because
identifier was generated with current timestamp as a base.