Revert ActiveRecord::Migration class from [7.1] to [5.1]

Reverted changing ActiveRecord::Migration class from [7.1]
to [5.1] (this was done as part of the feature branch rebase
on master)

Also added lint fixes

Author: lenikadali

backend/db/migrate/20160101154821_create_extensions.rb

@@ -1,4 +1,4 @@
-class CreateExtensions < ActiveRecord::Migration[7.1]
+class CreateExtensions < ActiveRecord::Migration[5.1]
   def change
     enable_extension "pg_trgm"
   end

backend/db/migrate/20160106154821_create_users.rb

@@ -1,4 +1,4 @@
-class CreateUsers < ActiveRecord::Migration[7.1]
+class CreateUsers < ActiveRecord::Migration[5.1]
   def change
     create_table :users do |t|
       ## Database authenticatable

backend/db/migrate/20160119185831_create_profiles.rb

@@ -1,4 +1,4 @@
-class CreateProfiles < ActiveRecord::Migration[7.1]
+class CreateProfiles < ActiveRecord::Migration[5.1]
   def change
     create_table :profiles do |t|
       t.belongs_to :user, index: true, foreign_key: true

backend/db/migrate/20160128112500_create_conditions.rb

@@ -1,4 +1,4 @@
-class CreateConditions < ActiveRecord::Migration[7.1]
+class CreateConditions < ActiveRecord::Migration[5.1]
   def up
     create_table :conditions do |t|
       t.boolean :global, default: true

backend/db/migrate/20160128114341_create_user_conditions.rb

@@ -1,4 +1,4 @@
-class CreateUserConditions < ActiveRecord::Migration[7.1]
+class CreateUserConditions < ActiveRecord::Migration[5.1]
   def change
     create_table :user_conditions do |t|
       t.belongs_to :user, index: true, foreign_key: true

backend/db/migrate/20160128191053_create_symptoms.rb

@@ -1,4 +1,4 @@
-class CreateSymptoms < ActiveRecord::Migration[7.1]
+class CreateSymptoms < ActiveRecord::Migration[5.1]
   def up
     create_table :symptoms do |t|
       t.boolean :global, default: true

backend/db/migrate/20160128191329_create_user_symptoms.rb

@@ -1,4 +1,4 @@
-class CreateUserSymptoms < ActiveRecord::Migration[7.1]
+class CreateUserSymptoms < ActiveRecord::Migration[5.1]
   def change
     create_table :user_symptoms do |t|
       t.belongs_to :user, index: true, foreign_key: true

backend/db/migrate/20160128210332_create_trackings.rb

@@ -1,4 +1,4 @@
-class CreateTrackings < ActiveRecord::Migration[7.1]
+class CreateTrackings < ActiveRecord::Migration[5.1]
   def change
     create_table :trackings do |t|
       t.belongs_to :user, index: true, foreign_key: true

backend/db/migrate/20160129063945_create_treatments.rb

@@ -1,4 +1,4 @@
-class CreateTreatments < ActiveRecord::Migration[7.1]
+class CreateTreatments < ActiveRecord::Migration[5.1]
   def up
     create_table :treatments do |t|
       t.boolean :global, default: true

backend/db/migrate/20160129064538_create_user_treatments.rb

@@ -1,4 +1,4 @@
-class CreateUserTreatments < ActiveRecord::Migration[7.1]
+class CreateUserTreatments < ActiveRecord::Migration[5.1]
   def change
     create_table :user_treatments do |t|
       t.belongs_to :user, index: true, foreign_key: true