Grow the Reading.degrees_f column

sometimes a probe will report a wacky temperature, but we should record
it even so

rattail_tempmon/db/alembic/script.py.mako

@@ -1,5 +1,5 @@
 # -*- coding: utf-8; mode: python -*-
-# -*- coding: utf-8 -*-
+# -*- coding: utf-8; -*-
 """${message}
 
 Revision ID: ${up_revision}

rattail_tempmon/db/alembic/versions/75c09e11543c_grow_degrees.py

@@ -0,0 +1,33 @@
+# -*- coding: utf-8; -*-
+"""grow degrees
+
+Revision ID: 75c09e11543c
+Revises: 76d52bb064b8
+Create Date: 2017-08-05 12:50:50.093173
+
+"""
+
+from __future__ import unicode_literals, absolute_import
+
+# revision identifiers, used by Alembic.
+revision = '75c09e11543c'
+down_revision = u'76d52bb064b8'
+branch_labels = None
+depends_on = None
+
+from alembic import op
+import sqlalchemy as sa
+import rattail.db.types
+
+
+
+def upgrade():
+
+    # reading
+    op.alter_column('reading', 'degrees_f', type_=sa.Numeric(precision=8, scale=4))
+
+
+def downgrade():
+
+    # reading
+    op.alter_column('reading', 'degrees_f', type_=sa.Numeric(precision=7, scale=4))