Add screenshot to front page

Also:
- Updated pythong_scripting.py example to show how to colorize text
- Updated contributing.md to show how to run code coverage in parallel using python-xdist and -nauto
- Updated contributing.md to talk more about looking at unit test results within the PR

1 files changed, 2 insertions, 0 deletions

diff --git a/README.md b/README.md
index 805ce5d6..b499eb41 100755
--- a/README.md
+++ b/README.md
@@ -13,6 +13,8 @@ applications.  It provides a simple API which is an extension of Python's built-
 of cmd to make your life easier and eliminates much of the boilerplate code which would be necessary
 when using cmd.
 
+[![Screenshot](cmd2.png)](https://github.com/python-cmd2/cmd2/blob/master/cmd2.png)
+
 
 Main Features
 -------------