added decimalSeparator and thousandSeparator properties.
issue #48

Fixes #373

- update composer json to chosse right path
- set vendorPath in application config if not default

`$this` -> `$self`

PHP supports exception stacks since 5.3 so we should use it.
Also Errorhandler is now able to display the stack: #297

make sure all information is displayed
Fixes comment by @creocoder issue #408
https://github.com/yiisoft/yii2/pull/408#issuecomment-18454179