Move to version to 19.3.0 for release

- Also update changes for 19.3.0
- Add in missing 18.8.0 changes into README.md too

Tested via building:
```
python setup.py sdist
python setup.py bdist_wheel
```

Author: cooperlees

README.rst

@@ -239,9 +239,20 @@ Change Log
 19.3.0
 ~~~~~~
 
+* allow 'mcs' for metaclass classmethod first arg (PyCharm default)
+* Introduce B011
+* Introduce B009 and B010
+* Exclude immutable calls like tuple() and frozenset() from B008
 * For B902, the first argument for metaclass class methods can be
   "mcs", matching the name preferred by PyCharm.
 
+18.8.0
+~~~~~~
+
+* black format all .py files
+* Examine kw-only args for mutable defaults
+* Test for Python 3.7
+
 18.2.0
 ~~~~~~
 

bugbear.py

@@ -9,7 +9,7 @@
 import pycodestyle
 
 
-__version__ = "18.8.0"
+__version__ = "19.3.0"
 
 LOG = logging.getLogger("flake8.bugbear")