Add .coverage. to Python.gitignore

When using `coverage -p` to get coverage for test runs in several environments coverage creates files on the form .coverage.hostname.timestamp.

Python.gitignore

@@ -37,6 +37,7 @@ pip-delete-this-directory.txt
 htmlcov/
 .tox/
 .coverage
+.coverage.*
 .cache
 nosetests.xml
 coverage.xml