Make fid nullable

I'm not totally sure what we do with sources with no FID, but we are
getting it from OFXHome so I'm going to keep it

alembic/versions/3ec1289eae7a_ofxaccount_fid_nullable.py

@@ -0,0 +1,28 @@
+"""ofxaccount_fid_nullable
+
+Revision ID: 3ec1289eae7a
+Revises: 3bac184298c9
+Create Date: 2016-07-20 15:36:28.157723
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '3ec1289eae7a'
+down_revision = '3bac184298c9'
+branch_labels = None
+depends_on = None
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+def upgrade():
+    op.alter_column('ofxsource', 'fid',
+               existing_type=sa.VARCHAR(length=255),
+               nullable=True)
+
+
+def downgrade():
+    op.alter_column('ofxsource', 'fid',
+               existing_type=sa.VARCHAR(length=255),
+               nullable=False)

vanth/tables.py

@@ -44,7 +44,7 @@ CreditCard = table('credit_card',
 
 OFXSource = table('ofxsource',
     Column('name',              String(255),     nullable=False), # The name of the institution such as 'America First Credit Union'
-    Column('fid',               String(255),     nullable=False), # The FID of the institution, such as 54324
+    Column('fid',               String(255),     nullable=True), # The FID of the institution, such as 54324
     Column('bankid',            String(255),     nullable=True), # The bank ID of the institution such as 324377516.
                                                                   # This may be a routing number
     Column('url',               String(4096),    nullable=False), # The base URL for the ofxsource