Use dotenv to load .env configurations

Gemfile

@@ -28,6 +28,7 @@ gem "sentry-raven"
 group :development, :test do
   # Call 'byebug' anywhere in the code to stop execution and get a debugger console
   gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
+  gem 'dotenv-rails'
 end
 
 group :development do

Gemfile.lock

@@ -66,6 +66,10 @@ GEM
     crass (1.0.6)
     declarative (0.0.10)
     declarative-option (0.1.0)
+    dotenv (2.7.5)
+    dotenv-rails (2.7.5)
+      dotenv (= 2.7.5)
+      railties (>= 3.2, < 6.1)
     erubi (1.9.0)
     faraday (1.0.1)
       multipart-post (>= 1.2, < 3)
@@ -216,6 +220,7 @@ PLATFORMS
 DEPENDENCIES
   bootsnap (>= 1.4.2)
   byebug
+  dotenv-rails
   google-api-client
   jbuilder
   listen