Added example for dividers to bootstrap Nav

fixes #1284
Correct Nav.php comments/PHP doc to reflect BS3 dropdown support.

Corrected the example and doc to highlight allowed dropdown support in Bootstrap 3.
Correct Nav.php comments/PHP doc to reflect BS3 dropdown support.

Updated tabs
Correct Nav.php comments/PHP doc to reflect BS3 dropdown support.

Removed edited author ref.
Merge pull request #1291 from kartik-v/patch-3

Correct Nav.php comments/PHP doc to reflect BS3 dropdown support.
Merge branch 'master' of github.com:yiisoft/yii2 into sphinx
yii\sphinx\Command reworked to extend yii\db\Command.
yii\sphinx\DataReader removed.
Redundant typecast removed from yii\sphinx\ActiveRecord::create()
Docs for Sphinx extension updated.
Fixes #1222: refactored jui/Widget, intorduced jui/Slider and jui/SliderInput
fixed typo
Merge branch 'master' into redis

* master: (613 commits)
  fixed typo
  Fixes #1222: refactored jui/Widget, intorduced jui/Slider and jui/SliderInput
  Correct Nav.php comments/PHP doc to reflect BS3 dropdown support.
  Correct Nav.php comments/PHP doc to reflect BS3 dropdown support.
  Correct Nav.php comments/PHP doc to reflect BS3 dropdown support.
  Added example for dividers to bootstrap Nav
  Checkboxlist documentation fix
  Added "Using controller action to render errors"
  Fix doc
  Renamed DetailView attribute type to format
  encode email in Formatter
  Added default status code setting.
  "yii\swiftmailer\Mailer" transport setup has been advanced to support constructor arguments and plugins.
  fix rbac select statement
  Comments cleanup.
  Reverted closeButton
  Nomenclature and code realignment.
  better nginx config
  guide about using bootstrap less files
  Include Schema in new migrations by default
  ...

Conflicts:
	framework/yii/db/ActiveRecord.php
	framework/yii/db/ActiveRelation.php
	tests/unit/data/config.php
"yii\swiftmailer\Mailer::createSwiftObject()" simplified.
refactored redis AR to relect the latest changes

- make use of traits
- short array
- better implementation of query findByPk
refactored Model and redis AR to allow drop of RecordSchema
cleanup redis AR
removed call to nonexistsend property
fixed broken UniqueValidator
Merge branch 'master' into elasticsearch

* master: (587 commits)
  fixed typo
  Fixes #1222: refactored jui/Widget, intorduced jui/Slider and jui/SliderInput
  Correct Nav.php comments/PHP doc to reflect BS3 dropdown support.
  Correct Nav.php comments/PHP doc to reflect BS3 dropdown support.
  Correct Nav.php comments/PHP doc to reflect BS3 dropdown support.
  Added example for dividers to bootstrap Nav
  Checkboxlist documentation fix
  Added "Using controller action to render errors"
  Fix doc
  Renamed DetailView attribute type to format
  encode email in Formatter
  Added default status code setting.
  "yii\swiftmailer\Mailer" transport setup has been advanced to support constructor arguments and plugins.
  fix rbac select statement
  Comments cleanup.
  Reverted closeButton
  Nomenclature and code realignment.
  better nginx config
  guide about using bootstrap less files
  Include Schema in new migrations by default
  ...

Conflicts:
	framework/composer.json
	tests/unit/data/config.php
added composer.json for yii2-dev package