Add git-up.bundler.autoinstall option. Closes aanand#13.

README.md

@@ -26,3 +26,5 @@ To set it within a project, run this command inside that project's directory:
     git config git-up.bundler.check true
 
 Replace 'true' with 'false' to disable checking.
+
+If you're even lazier, you can tell `git-up` to run `bundle install` for you if it finds missing gems. Simply set `git-up.bundler.autoinstall` to `true`, in the same manner. As above, it works globally or per-project, but make sure `git-up.bundler.check` is also set to `true` or it won't do anything.

lib/git-up.rb

@@ -147,7 +147,15 @@ def check_bundler
       ENV['BUNDLE_GEMFILE'] ||= File.expand_path('Gemfile')
       Bundler.setup
     rescue Bundler::GemNotFound, Bundler::GitError
-      puts 'Gems are missing.  You should `bundle install`.'.yellow
+      puts
+      print 'Gems are missing. '.yellow
+
+      if config("bundler.autoinstall") == 'true'
+        puts "Running `bundle install`.".yellow
+        system "bundle", "install"
+      else
+        puts "You should `bundle install`.".yellow
+      end
     end
   end