Better media_data sql table for images.

1. Change to the current primary key = media_entry id
   layout
2. Add gps_{latitude,longitude} to the table.

mediagoblin/media_types/image/models.py

@@ -1,18 +1,19 @@
 from mediagoblin.db.sql.models import Base
 
 from sqlalchemy import (
-    Column, Integer, Unicode, UnicodeText, DateTime, Boolean, ForeignKey,
-    UniqueConstraint)
+    Column, Integer, Float, ForeignKey)
 
 
 class ImageData(Base):
     __tablename__ = "image_data"
 
-    id = Column(Integer, primary_key=True)
+    # The primary key *and* reference to the main media_entry
+    media_entry = Column(Integer, ForeignKey('media_entries.id'),
+        primary_key=True)
     width = Column(Integer)
     height = Column(Integer)
-    media_entry = Column(
-        Integer, ForeignKey('media_entries.id'), nullable=False)
+    gps_longitude = Column(Float)
+    gps_latitude = Column(Float)
 
 
 DATA_MODEL = ImageData