Add --no-rc flag for more reliable local testing

The rspec-rails acceptance tests use `rails new` to generate a sample
app for running tests. If a developer running the rspec-rails test suite
has a `.railsrc` file, this will affect the app that is generated,
causing specs to fail.

This commit fixes this by passing the `--no-rc` flag so that `rails new`
ignores the developer's local `.railsrc`.

Author: mattbrictson

Rakefile

@@ -60,7 +60,7 @@ namespace :generate do
 
       # Rails 4 cannot use a `rails` binstub generated by Bundler
       sh "rm -f #{bindir}/rails"
-      sh "bundle exec rails new ./tmp/example_app --skip-javascript --skip-sprockets --skip-git --skip-test-unit --skip-listen --skip-bundle --template=example_app_generator/generate_app.rb"
+      sh "bundle exec rails new ./tmp/example_app --no-rc --skip-javascript --skip-sprockets --skip-git --skip-test-unit --skip-listen --skip-bundle --template=example_app_generator/generate_app.rb"
 
       in_example_app do
         sh "./travis_retry_bundle_install.sh 2>&1"
@@ -183,7 +183,7 @@ namespace :no_active_record do
 
         # Rails 4 cannot use a `rails` binstub generated by Bundler
         sh "rm -f #{bindir}/rails"
-        sh "bundle exec rails new #{example_app_dir} --skip-active-record --skip-javascript --skip-sprockets --skip-git --skip-test-unit --skip-listen --skip-bundle --template=example_app_generator/generate_app.rb"
+        sh "bundle exec rails new #{example_app_dir} --no-rc --skip-active-record --skip-javascript --skip-sprockets --skip-git --skip-test-unit --skip-listen --skip-bundle --template=example_app_generator/generate_app.rb"
 
         in_example_app(:app_dir => example_app_dir) do
           sh "./travis_retry_bundle_install.sh 2>&1"