Fixed gate by Updating Gemfile to pin Rake to 10.1.1

The latest Rake update requires Ruby >= 1.9. Bundler in the
current gate uses 1.8.x. This update fixes the gate by pinning
Rake to the last known working version.

Change-Id: I657d0ca1bc9cf9edfaaf9d1393eecc54ac4e196e