Introduce Application class

The newly added Application class represents a runnning application.
ApplicationProcessManager & RuntimeRegistry classes were removed.

Issue: Test system needs to be rewritten as it relies on the removed RuntimeRegistry.
Adapt in-browser testing system to the design changes.

Adapt in-Browser testing system to the RuntimeRegistry removal.
Added Application is_active() and Close() methods

Added Application is_active() and Close() methods
Prepare ApplicationService for managing multiple apps.

Prepare ApplicationService for managing multiple apps: it stores now scoped_vector of applications.
The ApplicationService interaface was cleaned.
Applcation Observer API was introduced to notify ApplicationService that the app has been closed.
Make ApplicationSystem own ApplicationStorage

Make ApplicationSystem own ApplicationStorage (application data storage actually) in order to split data storage and ApplicationService as those two objects should be treated separately.
Add render process host id getter to the Application class.

Add render process host id getter to the Application class - it will be used in the extensions to identify the corresponding app.
Fix browser tests regressions

1) An application should be present in "active applications" list even before it is launched, otherwise a protocol handler won't be registered for it
2) We should make sure that applications can be launched only from local directory URLs (not local file URLs)