added before and after actions

+ before initializes the db
+ after cleans the db

spec/create_spec.rb

@@ -13,6 +13,12 @@ end
 
 describe "Submit API request to create new link" do
   include Rack::Test::Methods
+  before :each do
+    @links = Sequel.sqlite("db/#{ENV['DB_NAME']}")[:links]
+  end
+  after :each do
+    @links.delete
+  end
   it "should return link data in json format when a valid url is entered" do
     data = {
       url: 'http://google.com'