added validation to the achievement
added validation to the language
added problem validation
updated solution validation and fixed broken tests
added validation for the user
added more user validation
updated the errors for validation to be bootstrapafied
Merge remote-tracking branch 'origin/feature/validation' into dev

Conflicts:
	app/assets/stylesheets/scaffolds.css.scss
	app/models/user.rb
	app/views/users/_form.html.erb
	test/fixtures/users.yml
	test/functional/users_controller_test.rb