Changed elasticsearch AR primary key handling

now supports mapped primary key when _id is part of source with an
alias.
Added --prefer-dist to all docs

1. It results in much smaller download and takes less disk space (25MB instead of 180MB for yii-basic + dependencies).
2. It requires less utilities to be installed (no VCS binaries required).
3. It takes less time to install dependencies.
Fixed URL parsing so it's now properly giving 404 for URLs like `http://example.com//////site/about`
doc fixes.
added laravel like touch() method to AutoTimestamp
fixed typo
Fixes #1791: support ON condition for relational query.
fixes #1811
Update view.md
Merge pull request #1813 from CodeBull/patch-1

Update view.md
Fixes #1791
Fixes #1791.
Fixes #1791.
Merge branch 'master' of github.com:yiisoft/yii2

Conflicts:
	framework/yii/db/ActiveQuery.php
Fixed test break.
Further cleanup.
added unit test for twig renderer

verify #1755 works
Fix doc for generateSalt.

$cost must be in range 4-31.
Merge pull request #1816 from Crypt/hotfix/Hotfix-PHPDoc

Fix doc for generateSalt.
Fixes #1791