Fixing bug caused by typo in core/Config.php (caused non-existant config sections to contain old superuser bridge info on first access).
Maintain accidental default behavior due to old typo bug (return empty array() when config section doesn't exist in INI config).
Added AJAX form directive for angularjs.
Merge pull request #6399 from piwik/angular_forms

Added angular directive that automates logic for AJAX forms.
Add isSubmitting property to piwik-ajax-form directive and make sure child elements can access scope.
Forgot to uncomment commented out code.
Simplified a Log::warning() call
Refactorings in ScheduledReports to remove useless indentation

I have refactored the code a bit to make it (hopefully) more readable. I have replaced this:

```php
if (self::manageEvent($reportType)) {
    // do something
}
```

By this:

```php
if (! self::manageEvent($reportType)) {
    return;
}

// do something
```

It's not much but it removes one level of indentation in almost the whole class, which is kind of nice.

FYI, this is one of the "object calisthenics" rules.