Add package creation date

Fixes #32

migrations/versions/13113e5710da_.py

@@ -0,0 +1,28 @@
+"""empty message
+
+Revision ID: 13113e5710da
+Revises: ead35f7d446c
+Create Date: 2018-05-23 20:18:07.606646
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '13113e5710da'
+down_revision = 'ead35f7d446c'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column('package', sa.Column('created_at', sa.DateTime(), nullable=False))
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column('package', 'created_at')
+    # ### end Alembic commands ###