Final release notes and version bump for 5.0

docs/releases/v5.0.0.rst

 What's new in Tornado 5.0
 =========================
 
-In progress
+Mar 5, 2018
 -----------
 
 Highlights
@@ -322,6 +322,8 @@ Other notes
   garbage collection.
 - `.RedirectHandler` now copies any query arguments from the request
   to the redirect location.
+- If both ``If-None-Match`` and ``If-Modified-Since`` headers are present
+  in a request to `.StaticFileHandler`, the latter is now ignored.
 
 `tornado.websocket`
 ~~~~~~~~~~~~~~~~~~~

setup.py

@@ -103,7 +103,7 @@ http://api.mongodb.org/python/current/installation.html#osx
 
 kwargs = {}
 
-version = "5.0b1"
+version = "5.0"
 
 with open('README.rst') as f:
     kwargs['long_description'] = f.read()

tornado/__init__.py

@@ -24,5 +24,5 @@ from __future__ import absolute_import, division, print_function
 # is zero for an official release, positive for a development branch,
 # or negative for a release candidate or beta (after the base version
 # number has been incremented)
-version = "5.0b1"
-version_info = (5, 0, 0, -98)
+version = "5.0"
+version_info = (5, 0, 0, 0)