Fixes #1965: `Controller::findLayoutFile()` returns incorrect file path when layout name starts with a slash
Fixes #1959 : compare model attribute with value/uncheck options
init of advanced application now allows to specify answer for overwriting files  via init --overwrite=n
Merge pull request #1971 from klevron/1959

Fixes #1959 : compare model attribute with value/uncheck options
Optimized #1959 code a bit
po file generatin added.
Files are generated using message/extract command.
E.g.: ./yii message/extract message/config.php po
Merge pull request #1973 from SergeiKutanov/po_generation

po file generating added.
Fixes #1973: Re-implemented solution for `yii message/extract` is now able to generate `.po` files
A bit less stricter check as suggested by @qiang: https://github.com/yiisoft/yii2/commit/2aa8fc71714134feac3f0a09dd61837d920be534
Fixes #1963: mentioned $jsOptions, $cssOptions and $publishOptions in assets guide
po filles generation.
All the quotation marks must be screened by adding a backslash before them. Otherwise we cannot generate .mo file.
Fix
MongoDB ActiveRecord uit test advanced to check integer value handling.
Merge branch 'master' of github.com:yiisoft/yii2
Merge pull request #1978 from marsuboss/patch-1

Fix translation french
code style fixed
Update upgrade-from-v1.md

Text amended as "A new method" was referring to two. CHanged the text to "New methods".
Merge pull request #1980 from surek/patch-1

Update upgrade-from-v1.md
po now supports obsolete messages
Add dutch translations