Fix packagist links in readme
Merge pull request #77 from filbertkm/readme

Fix packagist links in readme
Check that vendor/autoload.php exists

If we install property suggester via composer,
by including it in the Wikidata "build", in
MediaWiki's composer.json or other such setup
then autoload.php will be elsewhere and handled
elsewhere.
Merge pull request #78 from filbertkm/autoload

Check that vendor/autoload.php exists