Update flask-signup-datasources.rb
Update flask-signup-datasources.rb

Use t2.micro by default for database instance
amyzhang0330/py-flask-signup,gavinaws/py-flask-signup-datasources,amyzhang0330/py-flask-signup,gavinaws/py-flask-signup-datasources,gavinaws/py-flask-signup-datasources,amyzhang0330/py-flask-signup