Fix baking snapshots

[HavokInspiration]

After a snapshot was baked, the connection and the plugin options should be propagated to the mark_migrated dispatched Shell.
Not doing so resulted in the mark_migrated call to be executed with the default connection which was unexpected and caused problems.

I know the tests and the mark_migrated shell dispatching seems weird but I actually can put anything in place of the $dispatchCommand and it would work. What matters is the content of the $_SERVER['argv'] variable (if anyone knows why and would care to explain, I'll be glad).
But I still need to build a correct string for the tests.

Should fix #88

[markstory]

I really wish phinx had a less gross way of integrating sub commands.

[HavokInspiration]

Yeah me too.
I looked it up a bit and it is currently the only way I found.
I'll give it another shot just in case.

Edit : on second thoughts, we are in a "bake context". phinx might not be the problem here. Anyway, I'll investigate this.

[HavokInspiration]

@markstory I found a way to prevent the dirty stuff when dispatching the Shell.

I think that in a more general way, dispatching a migrations shell currently does not work.
I found out that the way the Symfony console package is built, it uses the original command as input arguments. Which means that when doing bin/cake bake migration_snapshot initial, the dispatched command is not the one the component auto-parses ; instead it is bake migration_snapshot initial that is used.
This is why I have to manually built it and pass it to the MigrationsDispatcher::run() method on each call.

[markstory]

Do you need to modify $_SERVER['argv'] now that you're passing ArgvInput?

[HavokInspiration]

Well, probably not.
I'll remove it and see.

[markstory]

Looks great 👍

[HavokInspiration]

@markstory You were right :)