[FEATURE] Internal cache in ConfigurationService
[TASK] Retrieve "stored variable" cache by stricter key

This takes into consideration which variable is requested (in any Flux extension, this would be "storage" so no impact there), the paths (these could change dynamically in a ConfigurationProvider on the same page, i.e. in multiple content elements using the same ConfigurationProvider and should prevent some undesired reuse) and finally the section name that contains the variable to retrieve (again in almost all cases would be "Configuration" but also could be dynamically set by ConfigurationProviders).
[TASK] Use existing internal cache in PageService for template configurations

Stores the selected template and sub-template for a page by uid, saving multiple executions of root line retrieval and work space overlays.
[TASK] Internally cache root line affected FlexForm source in PageService
[TASK] When reading all registered extensions' registrations, cache each internally

This prepares the internal caches for any subsequent requests for individual extension's configurations.
Merge pull request #26 from NamelessCoder/caches

[TASK] Improve performance through internal caches