Revert "(Maint) Add spec/functions to rake test task"

This reverts commit dbe3c8ecf6.

Because testing these against Puppet 2.6.x is causing failures.  These
need to be cleaned up, but I want to leave and this was the behavior
before I tried to "fix" it.

Rakefile

@@ -5,7 +5,7 @@ task :default => [:test]
 
 desc 'Run RSpec'
 RSpec::Core::RakeTask.new(:test) do |t|
-  t.pattern = 'spec/{unit,functions}/**/*.rb'
+  t.pattern = 'spec/{unit}/**/*.rb'
   t.rspec_opts = ['--color']
 end