Add travis CI config

.travis.yml

+osx_image: xcode7.2
+language: objective-c
+script: ./ci/script.sh

Gemfile

+source 'https://rubygems.org'
+
+gem 'xcpretty'
+gem 'xcpretty-travis-formatter'

Gemfile.lock

+GEM
+  remote: https://rubygems.org/
+  specs:
+    rouge (1.10.1)
+    xcpretty (0.2.2)
+      rouge (~> 1.8)
+    xcpretty-travis-formatter (0.0.4)
+      xcpretty (~> 0.2, >= 0.0.7)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  xcpretty
+  xcpretty-travis-formatter
+
+BUNDLED WITH
+   1.10.6

ci/script.sh

+#!/usr/bin/env bash
+
+set -euo pipefail
+
+xcrun xcodebuild build test \
+  NSUnbufferedIO=YES \
+  -project iTerm2.xcodeproj \
+  -scheme iTerm2 \
+  -sdk macosx \
+    | xcpretty -c -f `xcpretty-travis-formatter`