Fixes #1017.
Fixes #996.
Fixed asset file registration with extra leading slashes.
Fixes #1004.
Short array syntax
typo fix
Fixed bug in AssetBundle::registerAssets().
Better handling of trying to configure already instantiated component
Fixed ActiveForm
Refactored instanceof in Module into method in Application
Refactored Module::setBasePath to remove instanceof condition
Better Module::init refactoring
Removed unnecessary call
Revert "Better handling of trying to configure already instantiated component"

This reverts commit 6b15768a3f8613edaf611b13b4f55e3b60773ab6.
Merge branch 'master'
Merge branch 'master' of github.com:yiisoft/yii2
typo fix.
Fixed test break.
Extension installer wip
Extension installer wip