fix test_insert_vocabs test

Closes #5 by:

1. Fixing the actual error that was causing the test to fail.
2. Updating the Gemfile to consolidate ruby version and dependencies. Please be aware ruby version was upgraded to 2.4.0.

transform_csv/test/transform_test.rb

@@ -52,7 +52,7 @@ class TransformTest < Minitest::Test
     vocab_uri = "https://purl.org/geojson/vocab#"
     transform = Transform.new({
       source: @csv_source,
-      vocab: {geojson: geojson_vcab_uri, iss_global: @vocab_url}
+      vocab: {geojson: @vocab_uri, iss_global: @vocab_url}
       })
 
     rdf_output = transform.create_vocab