Add "autoload" section to composer.json

This enables autoloading for applications that install this library
using Composer.
[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
[fix] Fix issue with undefined variable in Schema::flush()

It was a long day...
[dev] Remove completed todo
[dev] Task::allowedScopes should be a static property

It's pointless to have it as instance variable
[new] Tweak the Task class' API to allow reading current Task configuration
[dev] Simplify naming of conversion methods
[dev] Simplify method call in Link::__construct()
[new] ObjectGUID is now displayed exactly as AD tools show it
[new] Allow the Converter to accept attribute names as strings instead of requiring an instance of Attribute class
[new] Include highestcommitedusn in Link::rootDSE entry by default
[new] objectGuid is now returned for all retrieved objects automatically
[dev] Fix typo, it's double T in highestcommittedusn
[new] Implemented method for tracking changes in Active Directory