fix for issue 6076. avoid GlobIterator globbing to directories which it will subsequently fail to unlink() by appending *.* instead of just * to path in clearByNamespace() and clearByPrefix(). *.* will glob to both .dat and .tag extensions
add unit test for clearByNamespace. Attempting to write a unit test for clearByPrefix shows that it's actually not an issue (due to the prefix itself differentiating a file from a dir), so revert my change to clearByPrefix
add fix and unit test for the case where Filesystem::clearByPrefix() can try to remove a directory (eg if the prefix happens to collide with a partial md5 key), as pointed out by @marc-mabe in issue 6076
php_cs whitespace cleanup
Merge pull request #6077 from brettmc/zf6076

fix for issue 6076. avoid GlobIterator globbing to directories which it ...

Conflicts:
	tests/ZendTest/Cache/Storage/Adapter/FilesystemTest.php
Merge branch 'hotfix/6077'

Close #6077
Fixes #6076