adding steadymark tests to Makefile

Makefile

@@ -3,6 +3,7 @@ all: check_dependencies unit functional
 filename=httpretty-`python -c 'import httpretty;print httpretty.version'`.tar.gz
 
 export HTTPRETTY_DEPENDENCIES:= nose sure
+export PYTHONPATH:= ${PWD}
 
 check_dependencies:
 	@echo "Checking for dependencies to run tests ..."
@@ -18,6 +19,10 @@ functional: clean
 	@echo "Running functional tests ..."
 	@nosetests -s --verbosity=2 --with-coverage --cover-erase --cover-inclusive tests/functional --cover-package=httpretty
 
+doctests: clean
+	@echo "Running documentation tests tests ..."
+	@steadymark README.md
+
 clean:
 	@printf "Cleaning up files that are already in .gitignore... "
 	@for pattern in `cat .gitignore`; do rm -rf $$pattern; done