SQLite support for disable integrity check

This is a porting from yii framework version 1.
I need it to run functional tests with fixtures.
Changelog updated
Merge pull request #3544 from MDMunir/patch-1

Add $key to function parameter
updated upgrade info [skip ci]
Fixes #3542: Removed requirement to specify `extensions` in application config
Fixed changelog
Merge branch 'zeeke-patch-1'
Merge branch 'origin/master'
Fixes #2898: `yii\console\controllers\AssetController` is now using hashes instead of timestamps
Adjustments according to comments on #3575
Fixed asset controller tests
added more types to pgsql schema, better detection

fixes #3578
Include nightly HHVM builds into the build matrix
Merge pull request #3579 from DaSourcerer/travis-ci

[Travis CI] Include nightly HHVM builds into the build matrix
fix #3501 replace . when generating input ids
fixes #3473, allow precision in pgsql abstract timestamp
ignore composer.lock in applications (yii2-dev only)
fixed argument display in errorHandler
Merge branch 'master'

Conflicts:
	framework/CHANGELOG.md
Merge pull request #3575 from yiisoft/extensions-autoloading

Fixes #3542: Removed requirement to specify `extensions` in application config