874 pre commit hook (#876)

* Changed .*.py --> *.py to avoid .ipynb files having yapf linting error checks run on them.

* Added directions in README_developers.md to uninstall the pre-commit hook

* Fixed pre-commit hook to catch python files.

hooks/pre-commit

@@ -12,7 +12,7 @@ fi
 
 echo "Begin linting step using yapf formatting"
 linterrorfound=0
-for stagedfile in $(git diff --name-only --cached | grep *.py)
+for stagedfile in $(git diff --name-only --cached | grep ".*\.py")
 do
     yapf --diff --style .style.yapf $stagedfile
     ret=$?