Fix Berksfile, update gems

Berksfile

@@ -1,4 +1,4 @@
-site 'https://supermarket.chef.io'
+source 'https://supermarket.chef.io'
 
 metadata
 

Berksfile.lock

@@ -1,25 +1,24 @@
-{
-  "sources": {
-    "python": {
-      "path": "."
-    },
-    "minitest-handler": {
-      "locked_version": "1.1.2"
-    },
-    "apt": {
-      "locked_version": "2.3.4"
-    },
-    "yum": {
-      "locked_version": "3.0.2"
-    },
-    "build-essential": {
-      "locked_version": "1.4.2"
-    },
-    "python_test": {
-      "path": "./test/cookbooks/python_test"
-    },
-    "chef_handler": {
-      "locked_version": "1.1.4"
-    }
-  }
-}
+DEPENDENCIES
+  apt
+  build-essential
+  minitest-handler
+  python
+    path: .
+    metadata: true
+  python_test
+    path: test/cookbooks/python_test
+  yum
+
+GRAPH
+  apt (2.5.3)
+  build-essential (2.0.6)
+  chef_handler (1.1.6)
+  minitest-handler (1.3.2)
+    chef_handler (>= 0.0.0)
+  python (1.4.7)
+    build-essential (>= 0.0.0)
+    yum-epel (>= 0.0.0)
+  python_test (0.1.0)
+  yum (3.3.1)
+  yum-epel (0.5.1)
+    yum (~> 3.0)

Gemfile

@@ -1,5 +1,5 @@
 source 'https://rubygems.org'
 
-gem 'foodcritic', '>= 3.0.3'
-gem 'berkshelf', '~> 2.0'
-gem 'chefspec', '~> 3.0'
+gem 'foodcritic', '~> 3.0'
+gem 'berkshelf', '~> 3.1'
+gem 'chefspec', '~> 4.0'