Minor typo fix in PHP comment
Add deprecated notifications CSS/JS to new folder #124

These are the minified versions that shipped in v3.4.1. They will not
be changed in the future.
Add a new file in the core package to contain any deprecated functionality. See #124

For v3.5, it will contain a helper function which checks to see if the
current child/parent theme has a copy of the deprecated (and removed)
notifications template file.