Wrong Reactionary dependence

exports/atom.coffee requires package `reactionary` while atom only has `reactionary-atom-fork` as a dependence (https://github.com/atom/atom/blob/master/package.json#L53). Should require `reactionary-atom-fork` instead.

It's clear that `Reactionary` will soon be omitted from atom's module exports, but as long as fallbacks are provided, the `reactionary` package reference should be corrected. :)
Updated deprecation msg to reactionary-atom-fork
Add beginning of message system
Add a MessageManager to atom.messages
:memo:
Add some things to Message
Add specs for Message
nof
Export Message
Messages -> notifications
Use bug icon for fatal errors
Remove issue related stuff
Export Notification, not Message
Notification::getTimestamp()
Remove unnecessary error flash classes
Prepare 0.153.0 release
Add legacy panel classes to support old theme selectors

Signed-off-by: Max Brunsfeld <maxbrunsfeld@gmail.com>
Add legacy ‘from-top’ class at the view layer, not the model

This blends in to our approach with the other legacy panel classes.
Merge pull request #4264 from atom/bo-messages

Messages API implementation
Don’t apply ‘tool-panel’ class to modal panels