Fixed various docblocks
Only create a "config" instance if only it not yet created.

Make it consistent with changes to Illuminate\Database\Capsule\Manager
merged in laravel/framework#4598

Signed-off-by: crynobone <crynobone@gmail.com>
Merge branch '4.1' into 4.2
Merge branch '4.2' of github.com:laravel/framework into 4.2