Auto-detect namespace in smarty function component

For now we load components like: 
`{component name='SK_Component_Abstract'}`. 

With this change it is possible to also load it like this: 
`{component name='Component_Abstract' namespace='SK'}` 

which makes it possible to leave the `namespace` away. If so the function will try to auto detect the class in the highest namespace. 
e.g. `{component name='Component_Abstract'}`

INFO: This change is backwards-compatible so you don't have to change all your implementations.