adds target-exchange and initial migrations

api/target_exchange/models.py

@@ -0,0 +1,10 @@
+from api.database import (Model, SurrogatePK, db,
+                          Column, reference_col, relationship)
+
+
+class TargetExchange(SurrogatePK, Model):
+    __tablename__ = "target-exchange"
+    name = Column(db.String(255), unique=True, nullable=False)
+
+    def __init__(self, name, **kwargs) -> None:
+        Model.__init__(self, name=name, **kwargs)