deprecate dev extra in favor of requirements.txt in tests dir

Author: reinecke

Makefile

@@ -16,7 +16,7 @@ ccend = $(shell echo "\033[0m")
 # Helpful link to install development dependencies declared in setup.py
 define dev_deps_message
 $(ccred)You can install this and other development dependencies with$(newline)$(ccend)\
-$(ccblue)	pip install -e .[dev]$(newline)$(ccend)
+$(ccblue)	pip install -e . && pip install -r tests/requirements.txt$(newline)$(ccend)
 endef
 
 # variables

setup.py

@@ -371,14 +371,6 @@ def run(self):
             ),
         ],
     },
-    extras_require={
-        'dev': [
-            'check-manifest',
-            'flake8>=3.5',
-            'coverage>=4.5',
-            'urllib3>=1.24.3'
-        ],
-    },
 
     # because we need to open() the adapters manifest, we aren't zip-safe
     zip_safe=False,

tests/requirements.txt

@@ -0,0 +1,4 @@
+check-manifest
+flake8>=3.5
+coverage>=4.5
+urllib3>=1.24.3