Merge pull request #15 from backbone87/master

fix file handling in shadow copies and runonce path
Fix ContaoCommunityAlliance/Composer#76, do not execute system/runonce.php multiple times.
Auto-Reformat code
Create parent directory for symlink, if it does not exists.
Add provides to global project composer.json.
Fix the "provide" keyword, when adding shipped libraries.
Update localconfig.php only if it exists.

The composer classes for Contao 2 would only be added if the
localconfig.php exists, otherwise the installer fail with a "failed to
open stream" error.
use unlink() to remove stale symlinks instead of using the filesystem instance as the latter one uses file_exists().
Update artifact path only on windows.
Remove classes cache hack from localconfig.
Define supported contao version.
Introduce ConfigUpdateException when composer.json get modified.
Read swift version in Contao 3.2.
Conflict with composer client older than 0.7.10.
Conflict with contao 3.0.*.
Fix path issue when $source is "".
Allow the complete contao 2.11.x tree.
Re-run all runonces if the contao version change.
Make the RunonceExecutor multi-usablewq.
add info message when removing obsolete copies