DatabaseMap::getTableByPhpName($phpName) with no namespaces

Correctly add map namespace when **$phpName** has no backslash (e.g. namespaces are not used) to fix #614.

I did not write a unit test, but it should be focused checking **getTableByPhpName($phpName)** with **$phpName** being:
- _Foo_
- _FooBar_ 
- _myNameSpace\Foo_
- _myNameSpace\FooBar_
- _myNameSpace\FooBar\Baz_