Check exclude from downloaded composer.json
Merge pull request #2482 from oziks/fix-composer-archive-property

Check exclude from downloaded composer.json
Check exception code only if class ZipArchive exists

If is for example exception throwed when downloading tar archive on system without installed zip extension, PHP hangs on fatal error " Class 'ZipArchive' not found".
Merge pull request #2483 from JakubOnderka/patch-2

Check exception code only if class ZipArchive exists
Detect ~> misuse and suggest fix, fixes #2476