Add --add-field option to startmigration

[andrew@…]

Something like:

startmigration myapp --add-field fieldname

which would create the template with the appropriate add_column filled in already, and any necessary foreign keys, constraints, indices, etc.

[andrew]

Done in [108] and [109] - I've run it through a series of quick tests, but since I haven't yet got a testing framework up for startmigration, more testing is appreciated...