Adds bullet to dev & test, but makes it visible only on-demmand

The logs are always stored in log/bullet.log

If you run the specs with `BULLET=true bin/rspec`:
* Any feature test which makes bullet angry will fail

If you run rails with `BULLET=true bin/rails s`:
* It will print the bullet logs in both the rails log and the bullet log
* It will show a footer on each page with the N+1 queries etc.

config/environments/development.rb

@@ -44,4 +44,13 @@ Rails.application.configure do
   # config.action_view.raise_on_missing_translations = true
 
   config.cache_store = :null_store
+
+  config.after_initialize do
+    Bullet.enable = true
+    Bullet.bullet_logger = true
+    if ENV['BULLET']
+      Bullet.rails_logger = true
+      Bullet.add_footer = true
+    end
+  end
 end

config/environments/test.rb

@@ -45,4 +45,13 @@ Rails.application.configure do
   # config.action_view.raise_on_missing_translations = true
 
   config.cache_store = :null_store
+
+  config.after_initialize do
+    Bullet.enable = true
+    Bullet.bullet_logger = true
+    if ENV['BULLET']
+      Bullet.raise = true # raise an error if n+1 query occurs
+    end
+  end
+
 end