Switch to SendGrid (remove sparkhost)

Gemfile

@@ -109,7 +109,6 @@ group :production, :staging do
   gem 'memcachier'
   gem 'newrelic_rpm'
   gem 'rails_12factor' # supresses heroku plugin injection
-  gem 'sparkpost_rails'
 end
 
 group :development do

Gemfile.lock

@@ -459,8 +459,6 @@ GEM
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)
-    sparkpost_rails (1.5.1)
-      rails (>= 4.0, < 5.3)
     sprockets (3.7.2)
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)
@@ -584,7 +582,6 @@ DEPENDENCIES
   sass-rails
   selenium-webdriver
   sidekiq
-  sparkpost_rails
   timecop
   uglifier
   unicorn

app.json

@@ -41,7 +41,7 @@
     "bonsai-elasticsearch",
     "memcachier",
     "newrelic",
-    "sparkhost"
+    "sendgrid"
   ],
   "buildpacks": [
     {

config/application.yml.example

@@ -81,7 +81,6 @@ GROWSTUFF_EMAIL: 'noreply@dev.growstuff.org'
 test:
   GROWSTUFF_SITE_NAME: Growstuff (test)
   GROWSTUFF_CAPYBARA_DRIVER: poltergeist
-  GROWSTUFF_EMAIL: 'noreply@test.growstuff.org'
 
 # Note: there is no good way to deploy settings from Figaro to
 # Travis-CI.  If you need env vars set there in order for tests to pass,
@@ -90,9 +89,7 @@ test:
 staging:
   GROWSTUFF_SITE_NAME: Growstuff (staging)
   GROWSTUFF_ELASTICSEARCH: "true"
-  GROWSTUFF_EMAIL: 'noreply@staging.growstuff.org'
 
 production:
   GROWSTUFF_SITE_NAME: Growstuff
   GROWSTUFF_ELASTICSEARCH: "true"
-  GROWSTUFF_EMAIL: 'noreply@growstuff.org'

config/environments/production.rb

@@ -82,12 +82,13 @@ Rails.application.configure do
   # Growstuff configuration
   config.action_mailer.default_url_options = { host: ENV['MAIL_SENDER_HOST'] }
 
-  ActionMailer::Base.smtp_settings = {
-    port:                 ENV['SPARKPOST_SMTP_PORT'],
-    address:              ENV['SPARKPOST_SMTP_HOST'],
-    user_name:            ENV['SPARKPOST_SMTP_USERNAME'],
-    password:             ENV['SPARKPOST_SMTP_PASSWORD'],
-    authentication:       :login,
+  config.action_mailer.smtp_settings = {
+    user_name: ENV['SENDGRID_USERNAME'],
+    password: ENV['SENDGRID_PASSWORD'],
+    domain: ENV['GROWSTUFF_EMAIL_DOMAIN'],
+    address: 'smtp.sendgrid.net',
+    port: 587,
+    authentication: :plain,
     enable_starttls_auto: true
   }
   ActionMailer::Base.delivery_method = :smtp