DatabaseMap::getTableByPhpName($phpName) with no namespaces #622 + test

Hi,

I add tests for @ciromattia 's PR #622

But I think there is something wrong with the `DatabaseMap` and namespaces

We set Name ( table name foo1 ), phpName ( Foo1 ), classname ( namespaced\Foo1 ), but we only use classname to get the right `TableMap`. 

The point is that the method `getTableByPhpName` never use `phpName` but only classname which is equals only for non namespaced classes.

@willdurand , @marcj , @staabm what should we do with this ?