[WIP] Add BuildFailure model

This model is in charge of keeping track of build failures that we find
when polling the Travis API.  Used to avoid spamming gitter with extra
notifications, but also can be used to identify that a branch has
previously been broken and now has been fixed.

Makes sense to also notify on the passing cases so others aren't taking
the time to investigate a failure when this has already been
investigated.

app/models/build_failure.rb

@@ -0,0 +1,19 @@
+class BuildFailure < ActiveRecord::Base
+  belongs_to :repo
+  belongs_to :branch
+
+  def notify
+    if should_notify?
+      update_attributes(:last_notified_at => Time.now)
+
+      BuildFailureNotifier.new(self).post_failure
+    end
+  end
+
+  def should_notify?
+    last_notified_at.nil? || last_notified_at > 1.day.ago
+  end
+
+  def still_broken?
+  end
+end

db/migrate/20200109223351_create_build_failures.rb

@@ -0,0 +1,12 @@
+class CreateBuildFailures < ActiveRecord::Migration
+  def change
+    create_table :build_failures do |t|
+      t.integer :repo_id
+      t.integer :branch_id
+      t.integer :travis_build_id
+
+      t.datetime :last_notified_at
+      t.timestamps
+    end
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20171006050814) do
+ActiveRecord::Schema.define(version: 20200109223351) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -48,6 +48,15 @@
     t.integer  "linter_offense_count"
   end
 
+  create_table "build_failures", force: :cascade do |t|
+    t.integer  "repo_id"
+    t.integer  "branch_id"
+    t.integer  "travis_build_id"
+    t.datetime "last_notified_at"
+    t.datetime "created_at"
+    t.datetime "updated_at"
+  end
+
   create_table "repos", force: :cascade do |t|
     t.string   "name",       limit: 255
     t.datetime "created_at"