Add Gemfile and puppet 4 checks

In anticipation of puppet 4, start trying to deal with puppet 4 things
that can be helpfully predicted by puppet lint plugins.

This patch also corrects lint errors caught by the
puppet-lint-empty_string-check plugin by changing the default value of
the $base parameter to be undef instead of empty string, which will be
evaluated the same when interpolated in a string, and by making the
$url parameter required.

Change-Id: Ic1146cbd44b589c5dfca10deb410301ef4d46528

.gitignore

@@ -0,0 +1,2 @@
+Gemfile.lock
+.bundled_gems/

Gemfile

@@ -0,0 +1,30 @@
+source 'https://rubygems.org'
+
+group :development, :test do
+  gem 'puppetlabs_spec_helper', :require => false
+
+  gem 'metadata-json-lint'
+  # This is nice and all, but let's not worry about it until we've actually
+  # got puppet 4.x sorted
+  # gem 'puppet-lint-param-docs'
+  gem 'puppet-lint-absolute_classname-check'
+  gem 'puppet-lint-absolute_template_path'
+  gem 'puppet-lint-trailing_newline-check'
+
+  # Puppet 4.x related lint checks
+  gem 'puppet-lint-unquoted_string-check'
+  gem 'puppet-lint-empty_string-check'
+  gem 'puppet-lint-leading_zero-check'
+  gem 'puppet-lint-variable_contains_upcase'
+  gem 'puppet-lint-spaceship_operator_without_tag-check'
+  gem 'puppet-lint-undef_in_function-check'
+
+  if puppetversion = ENV['PUPPET_GEM_VERSION']
+    gem 'puppet', puppetversion, :require => false
+  else
+    gem 'puppet', '~> 3.0', :require => false
+  end
+
+end
+
+# vim:ft=ruby

manifests/init.pp

@@ -16,8 +16,8 @@
 #
 
 class project_config(
-  $url = '',
-  $base = '',
+  $url,
+  $base = undef,
 ) {
 
   $config_dir = Vcsrepo['/etc/project-config']