removed getPostParam() from Request, body is $_POST by default

fixes #2093
adjusted changeloadjusted changelogg
updated composer.json
Small typo in console-migrate.md
Merge pull request #2182 from Theill11/patch-1

Small typo in console-migrate.md
Added missing class header, used HEREDOC instead of echo
Added note about HTML5 inputs
Doc typo
Merge pull request #2186 from kate-kate/patch-1

Doc typo
Fixes #2175: QueryBuilder will now append UNION statements at the end of the primary SQL
more union fix.
fix the _only_ option in calls to FileHelper::findFiles()
Merge pull request #2188 from nineinchnick/2184-fix-findFiles

fix the _only_ option in calls to FileHelper::findFiles()
Fixes #2149: Added `yii\base\DynamicModel` to support ad-hoc data validation
updated classmap
added more tests.
fixed exclude paths in phpdoc command

fixes #2184
Merge branch 'master' of github.com:yiisoft/yii2

* 'master' of github.com:yiisoft/yii2:
  added more tests.
updated phpdoc properties
added missing use statement.