requirements target to use piptools as source to ensure correct setup (…

…#198)

* requirements target to use piptools as source to ensure correct setup

* Update target name to piptools-requirements

Makefile

@@ -14,6 +14,9 @@ clean: ## remove generated byte code, coverage reports, and build artifacts
 	rm -fr dist/
 	rm -fr *.egg-info
 
+piptools-requirements: ## install tools prior to requirements
+	pip install -q -r requirements/pip_tools.txt
+
 coverage: clean ## generate and view HTML coverage report
 	py.test --cov-report html
 	$(BROWSER) htmlcov/index.html
@@ -40,7 +43,7 @@ upgrade: ## update the requirements/*.txt files with the latest packages satisfy
 	mv requirements/test-reporting.tmp requirements/test-reporting.txt
 
 
-requirements: ## install development environment requirements
+requirements: piptools-requirements ## install development environment requirements
 	pip install -qr requirements/base.txt --exists-action w
 	pip-sync requirements/base.txt requirements/dev.txt requirements/test.txt