Extracted `Piwik::getJavascriptCode()` into a separate, non static class: `Piwik\Tracker\TrackerCodeGenerator`

`Piwik::getJavascriptCode()` is now deprecated in favor of the new class.
Removed `Piwik::getJavascriptCode()` and its deprecation notice: it wasn't an API method
refs #6015 hide no data in category message if search is used
this makes each call to CoreHome and others 200ms faster on my instance (10%)
Merge branch 'master' of github.com:piwik/piwik
refs #6452 remove existing notification before creating new one
Merge pull request #6446 from piwik/refactoring-tracker-code-generator

Extracted `Piwik::getJavascriptCode()` into a separate, non static class
refs #6417 added a simple test for creating archiveid
Fix artifacts link displayed for UI tests in travis.sh script.
Moving CronArchive token auth check to archive script since it is only for when the archive.php script is invoked from a web request.
Forgot to remove calls to initCheckCli in last commit.
Merge branch 'master' of github.com:piwik/piwik
refs #6413 always return a proper return code
refs #6413 reduce number of jobs in travis.

Not sure if this would work. We would basically only start a job for
1 x AngualarJS
1 x JavaScript
1 x All Tests with PHP 5.4 and MySQLi
3 x All tests with PDO (5.3.3, 5.5 and 5.6)
1 x Unit test with PHP 5.4 and PDO
1 x Integration test with PHP 5.4 and PDO
1 x System test with PHP 5.4 and PDO
= 9 jobs compared to about 18 before
Remove unused variable in CronArchive (CronArchive::$isCoreInited).
Fix CronArchive token_auth refactor.
Fix tests
Merge branch 'master' into 6413_reduceTravisJobs
Removed a test that was testing nothing and that failed depending on your system
The initSession method has not been changed

Reproduce the error: When changing the password of the user from "User settings", it throws an fatal error.

Why ? : The initSession method has not been changed in the processPasswordChange method of the UsersManager Controller class.