Add safety around accessing node for an OFD, clean-up xattr code for path vs. ofd
Add test for deleted node accessed via ofd
Add note about https://github.com/filerjs/filer/issues/314
Merge pull request #311 from humphd/xattr-null-node

Add safety around accessing node for an OFD, clean-up xattr code for path vs. ofd
Fix #245 - Forced the user to manually instantiate FileSystemShell objects