fix merging issues
Fixes #1671
remove use of dumb static variable
minor fixes.
Updated git-workflow.md to remove a false link

Replaced link to gitref.org to try.github.com as gitref.org is down.
Fixes #1604: fixed URL and cookie problems.
Refactored tests.
added frame method
Fixed DB query logging category.
Merge branch 'debug_module_improvements' of github.com:Ragazzo/yii2 into Ragazzo-debug_module_improvements

Conflicts:
	extensions/yii/debug/panels/DbPanel.php
CS fixes.
added html layout for mail component in basic app
Fixed typo
keep methods interface constant
Fixes #1631: Charset is now explicitly set to UTF-8 when serving JSON
Simplified tests.
added mail events before/after send
added test
Fixes #1681: Added support for automatically adjusting the "for" attribute of label generated by `ActiveField::label()`
doc fix
Typo fix.