Moved stopwatch and extension initialization. Resolves #1193

Moves the creation of the stopwatch component inside the provider
initialization and the initialization of extensions inside it's own
method. Added the call to initExtensions to the latest possible position
- after mountpoint initialization and before processing "before" handler
(which may have additional handler added by extensions).
Bumping version to 1.6.2
Hopefully fixing the Stack-issue. See #1207, #1204
Merge branch 'release/1.6'

Conflicts:
	app/src/Bolt/Application.php