Remove abortIf with an option in command

[roukmoute]

Feature Request

Q	A
New Feature	yes
RFC	no
BC Break	no

Summary

We have created our own template wich have a preUp and preDown.
Thoses methods use $this->abortIf(…).

So now this is not really necessary to keep this line in all our migration files: $this->abortIf($this->connection->getDatabasePlatform()->getName() !== 'postgresql', 'Migration can only be executed safely on \'postgresql\'.');

Do you accept a P.R. with a new option which if it is given it does not add this line?

[jwage]

Sure, we can include that as a new feature option in 2.1

[roukmoute]

Ok cool!
So I will make a P.R. shortly.

[jwage]

Awesome! Be sure to include an update to the documentation here https://github.com/doctrine/migrations/blob/master/docs/en/reference/configuration.rst