Fix PHPdoc in apps/files_sharing

using scrutinizer patch
Fix PHPdoc in OC\Share\Share and OCP\Share
Merge branch 'master' into type-hinting-sharing

Conflicts:
	apps/files_sharing/lib/share/file.php
	apps/files_sharing/tests/api.php
	lib/private/share/share.php
Some more params are optional
Better documentation for isValidSource function
Correct return type for getFilePath
Typo
Use 'boolean' as type instead of 'bool'
Merge pull request #8221 from owncloud/type-hinting-sharing

Type hinting fixes for sharing