(maint) Update Gemfile to use rspec 2.14.0

Prior to this commit, the Gemfile for strings did not specify which
version of rspec to use. When it started using rspec 3, the tests
that relied upon the rspec-html-matchers gem began to fail, likely
because that gem is not yet compatible with the new version of rspec.

Update the Gemfile so that we explicitly use an older version of
rspec to prevent tests from failing. We will have to either wait
for rspec-html-matchers to catch up or find a new way of testing
the HTML output before we can update to rspec 3.

Gemfile

@@ -10,11 +10,11 @@ puppetversion = ENV['PUPPET_VERSION']
 if puppetversion
   gem 'puppet', puppetversion
 else
-  gem 'puppet', '~> 3.6.2'
+  gem 'puppet'
 end
 
 group :test do
-  gem 'rspec'
+  gem "rspec", "~> 2.14.0", :require => false
   gem 'mocha'
   gem 'puppetlabs_spec_helper'
   gem 'rspec-html-matchers'