Add RESTful method support for html forms

This commit allows calls to `CHtml::form()`, `CHtml::beginForm`
`CActiveForm::$method` etc to accept verbs other than `post` and `get`,
e.g. `delete`, `put`, `patch` etc

This is implemented by detecting non `post`, `get`, converting to `post`
 and adding a hidden `_method` field, similar to how CSRF protection works.
update changelog
add absolutePaths option to CFileHelper::findFiles

if absolutePaths is true (by default), function will return absolute paths, otherwise the relative ones
mbstring fallback for CFileHelper::findFiles
code conv fix, charset specifying and docs improvement
Merge remote-tracking branch 'upstream/master' into patch-1
CHANGELOG updated
Merge remote-tracking branch 'upstream/master'
another way to return relative paths: findFilesRecursive main loop instead of findFiles post-processing
allow arrays in asc/desc properties of virtual attributes
updated CHANGELOG and added test
Merge pull request #2773 from nineinchnick/182-csort-asc-desc-arrays

allow arrays in asc/desc properties of virtual attributes
[Guide] Changing "crypt" to "CPasswordHelper"
 [ci skip]
[Guide] rolling back russian translations
 [ci skip]
Merge pull request #2786 from yiiframework-com-ua/uk_docs

[Guide] Changing "crypt" to "CPasswordHelper"
Added a check for the OK file upload code to avoid checking all the
alternatives when the upload was ok.
Return from the method in the file size error branch when the file was
not uploaded.
Added a check in the MIME type validation to only check MIME types if
the CUploadedFile's tempName is not empty.
Updated CHANGELOG
Updated CHANGELOG
Merge pull request #2790 from Rupert-RR/#2778_BUG_CFileValidator_General_exception_when_validating_MIME_types_for_file_whose_upload_failed_due_to_file_size

#2778 Bug - CFileValidator general exception when validating mime types for file whose upload failed
Correct invalid tags in the PHPdoc.