pin execjs version to 1.4.0

Change-Id: I3cafa727fccd5d1794f42387d667faabc142e769
Reviewed-on: https://gerrit.instructure.com/23544
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>
Tested-by: Cody Cutrer <cody@instructure.com>
Remove Gemfile.lock from repository

Run bundle install on all nodes during deploy
without the --deployment flag to foce generation
of Gemfile.lock. This removes any one developer's
machine from the deploy process.

Also folds in a commit from instructure/stable to
pin execjs at 1.4.0 as not doing so prevents
compiled assets from being generated.
Merge pull request #117 from grahamb/canvas-232-gemfile-bundle

Remove Gemfile.lock from repository