[Core] Added initial support for profiles
 * The StandardConfigurationLoader has been updated in order to be able to load different properties files depending on the active profile.
 * A profile is activated using the -Ddandelion.profile.active system property
 * Some reserved words are used to load preconfigured sets of configurations
    * "", "dev", "development" => each DandelionConfig entry is configured using the default dev value
    * "prod", "production" => each DandelionConfig entry is configured using the default prod value
 * Any custom profile name can be used. All configurations that are not specified in the corresponding properties file will be initialized with default dev values.
 * Plenty of configuration points have been renamed or added (toolAssetPrettyPrintingEnabled, toolBundleGraphEnabled, assetCachingEnabled, ...) for more consistency

Regarding #36, it only lacks variables substitution and corresponding tests obviously.
[Core] Finalized support for profiles
 * Added new utilities method allowing to perform variable substitution
 * At startup, a new finalization step is executed during the filling of the BundleStorage to perform variable substitution in asset locations
 * Asset names are now stored lowercase when deducted from the asset location (fixing a regression in bundles/assets exclusions)
 * Code cleaning (new comments, useless checks, ...)

Closes #36