Update manager.php

add caching to getUserGroupIds
Update manager.php

added description and blank lines in getUserGroupIds
Update manager.php

defined $uid in getUserGroupIds
Update manager.php
Update manager.php
Update manager.php
clean up function getUserGroupIds

clean up of function getUserGroupIds and improved caching mechanism of cachedUserGroupIds
modified caching mechanism in getUserGroupIds

removed cachedUserGroupIds, instead changed indexing in getUserGroups to groupId
adapted tests for a groupId indexed group array
make sure class file is loaded once
Fix AmazonS3 rmdir on the root
Fix amazon s3 rename overwrite
Fix copy overwrite for amazon s3
Skip test for unsuported feature for amazon s3
fix retrievel of group members and cache group members
group shares and combine permissions
unit tests for grouping of shares pointing to the same source
generateTarget() will always find a unique target
fix add user to group to work with grouped shares
fix unit tests