Added database tasks to Rakefile

Rakefile

@@ -1,5 +1,17 @@
 require 'bundler/setup'
 
+namespace :db do
+  desc 'Run migrations'
+  task :migrate, [:version] do |t, args|
+    require "sequel/core"
+    Sequel.extension :migration
+    version = args[:version].to_i if args[:version]
+    Sequel.connect('sqlite://data/destructo.db') do |db|
+      Sequel::Migrator.run(db, "db/migrations", target: version)
+    end
+  end
+end
+
 namespace :server do
   task :start do
     ENV['APP_ENV'] = 'production'