Automatic Xcode integration fails with Ruby 2.3.0+

[alykhank]

Tailor Version: v0.10.0

Swift Version: 2.2.1

Platform (Mac/Linux/Windows/CI): Mac

Installation Method: Homebrew

Steps to Reproduce Issue

Pre-requisite: Ruby 2.3.0+ installed (appears to work as expected with prior versions of Ruby).

1. tailor --xcode project.xcodeproj

Expected Behavior

No CLI output, Tailor Build Phase Run Script gets added to Xcode project.

Actual Behavior

$ tailor --xcode project.xcodeproj
/usr/local/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- xcodeproj (LoadError)
    from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
    from /var/folders/l3/bcv31sjn6g3b7tnkkc1w3rdm0000gn/T/xcode_integrate3118690974984677728rb:24:in `<main>'

Tailor Build Phase Run Script is not added to Xcode project.