Fixed: Typo in Makefile (#184)

Fixed typo in Makefile, section "Set up python interpreter environment": intalled --> installed

{{ cookiecutter.repo_name }}/Makefile

@@ -66,7 +66,7 @@ endif
 		@echo ">>> New conda env created. Activate with:\nsource activate $(PROJECT_NAME)"
 else
 	$(PYTHON_INTERPRETER) -m pip install -q virtualenv virtualenvwrapper
-	@echo ">>> Installing virtualenvwrapper if not already intalled.\nMake sure the following lines are in shell startup file\n\
+	@echo ">>> Installing virtualenvwrapper if not already installed.\nMake sure the following lines are in shell startup file\n\
 	export WORKON_HOME=$$HOME/.virtualenvs\nexport PROJECT_HOME=$$HOME/Devel\nsource /usr/local/bin/virtualenvwrapper.sh\n"
 	@bash -c "source `which virtualenvwrapper.sh`;mkvirtualenv $(PROJECT_NAME) --python=$(PYTHON_INTERPRETER)"
 	@echo ">>> New virtualenv created. Activate with:\nworkon $(PROJECT_NAME)"