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