table_exists should also consider the views

[dmathieu]

Something strange happened while changing the pull request's commits and my branch has been committed into my own fork.

So I'm reopening a pull request. This follows #1469

[jonleighton]

Hey,

It needs a test. You can add db-specific code to add a view in the postgres sql file in test/schemas, and then test that it works.

Also, we should probably automatically mark records as readonly if they come from a view. @tenderlove, what do you think?

Cheers

[dmathieu]

I've added a test.
However I don't think you should apply it now. I realize it doesn't work on mysql and sqlite either (which seems logical, but the original ticket, #379 didn't mention it).

I'll see what I can do for mysql and sqlite.

[dmathieu]

It now works for all adapters !

I completely agree with you about marking the model as readonly when it's a view.
If @tenderlove agrees with it, I'll look into that too.