Support third party autoloaders in Yii::import()

This commit adds support for loading namespaced classes
with third party autoloaders when using `Yii::import()`
and `Yii::createComponent()`. It means that you no longer
need to explicitly set aliases for each and every root
namespace you want to use in your app, which makes working
with composer much easier.

It uses reflection to autoload the class, preserving backwards
compatibility.

Fixes #2642.
Merge pull request #2723 from phpnode/2642-namespace-autoloading

Support third party autoloaders in Yii::import()
framework/messages/ja/yii.php updated
Merge pull request #2725 from softark/ja-update-2013-08-03

framework/messages/ja/yii.php updated
Add alias to imports when returning

addition to #2723 fixing issue #2642
Changed header case Content-type to Content-Type

fixes #2709 fixes #2726
Better fix for #2642

changes made after discussion in #2723
Update finnish translations
Merge pull request #2730 from janisto/messages_fi_update-5

Update finnish translations
ru: updated docs
ru: typo fixes
update german translation
Merge pull request #2731 from cebe/german-translation

update german translation
[UK] Updating docs
Merge pull request #2735 from yiiframework-com-ua/uk_docs

[UK] Updating docs
Added closing parentheses to verifyPassword instruction
Merge pull request #2743 from jpopesculian/patch-1

Added closing parentheses to verifyPassword instruction
[UK] Blog and guide updates
Merge pull request #2749 from yiiframework-com-ua/uk_docs

[UK] Blog and guide updates
CRedisCache UnitTest to verify #2750