Add in options to publish profile

[paupino]

Add in some further options:

• allow_drop_tables
• allow_drop_columns
• allow_drop_primary_constraints
• allow_drop_foreign_constraints

Perhaps we should also consider expanding the allow_unsafe_operations so that it is more explicit.

[paupino]

I think each of these likely needs a tri-state: Allow, Error, Ignore.

From there the items we need to consider are:

• drop_enum_values
• drop_tables
• drop_columns
• drop_primary_key_constraints
• drop_foreign_key_constraints

The last two are a little controversial for index modifications at present however I've now created a ticket to track this (#103)