update Gemfile.lock in order to fix the error in `rake spec'

when run `rake spec', it causes the error with the following message

    Pod::Informative: [!] The `master` repo requires CocoaPods 0.29.0 -
Update for CocoaPods 0.32
Set the Podfile to be defined in the Rakefile.
Fix output level so the UI module correctly prints expected output.
[README] Update for 0.14.1
Bump to cocoapods 0.32.1
Merge branch 'master' into hide_output_option