[fix] Schema: Fix permissions on newly created Schema folders ( was 644, now 755 )
[dev] Major rewrite of the adx.php bootstrap script

Now defines ADX_ROOT_PATH as the base path to the app and uses
DIRECTORY_SEPARATOR to handle file paths
[fix] Resolve problems with Schema caching / flushing / loading cached items
[fix] Fallback to CN as the RdnAttId if schema-based value is not present
[dev] Better handling for the Attribute::isResolvable property validation
[fix] Validate presence of isSingleValued in the schema cache before using it
[dev] Improve whitespace