Log applied migration id

[tamalsaha]

No description provided.

[rubenv]

I won't merge this: sql-migrate can be used as a library, where log output may not be desired.

[tamalsaha]

@rubenv, understood. We are using this as a lib. Having no logging was causing us to wonder when things failed. May there can be verbose option with default false to preserve current behavior.

[rubenv]

@tamalsaha What went wrong should be present in the error returned by Exec(), no?

[tamalsaha]

In our case, nothing went wrong, but it was also doing nothing. Sort of got stuck. We don't know what happened yet.