Bump to 2.2.1! The HackerNews followup release

* Simplepush backend (@tymm)
* Fix `ntfy done --pid` regression (@AilisObrian)
* Allow specifying title per-backend in the config
* Notifico! support (@eightnoteight)
* Fix bug with homedir shortening (@eightnoteight)
* Disable homedir shortening on Windows (@avamsi)
* internal cleanup (@avamsi)
* add missing PyObjC dependency for MacOS (@dcoeurjo)

ntfy/__init__.py

@@ -6,7 +6,7 @@
 from inspect import getargspec
 from .backends.default import DefaultNotifierError
 
-__version__ = '2.1.1'
+__version__ = '2.2.0'
 
 
 notifiers = dict.fromkeys(['default', 'darwin', 'linux', 'notifico',