Don't call Session->startId if session has already been started

This might not work with custom SessionStorageInterface implementations
but seems to work fine with the default native storage.

closes #33 / replaces #33
Merge branch 'master' into develop
Implement has() in config and array utils

Closes #37
add failing test for setting namespaced config vars before they are loaded
fix setting namespaced config vars before they are loaded
Merge branch 'master' into develop

Conflicts:
	src/Config/FileStore.php
	src/Kernel/Application.php
reorganize log provider
reorganize extension loader
enable yaml file caching