update development resources

fix tox to test examples again
add detox tox env for faster testing
clean up makefile, add tox target
add extra group for installing dev requirements
clean up contributing doc, build with docs
expand issue template
add pull request template

setup.py

@@ -48,14 +48,12 @@ import re
 import ast
 from setuptools import setup
 
-
 _version_re = re.compile(r'__version__\s+=\s+(.*)')
 
 with open('flask/__init__.py', 'rb') as f:
     version = str(ast.literal_eval(_version_re.search(
         f.read().decode('utf-8')).group(1)))
 
-
 setup(
     name='Flask',
     version=version,
@@ -76,6 +74,17 @@ setup(
         'itsdangerous>=0.21',
         'click>=4.0',
     ],
+    extras_require={
+        'dev': [
+            'blinker',
+            'greenlet',
+            'pytest>=3',
+            'coverage',
+            'tox',
+            'sphinx',
+            'sphinxcontrib-log-cabinet'
+        ],
+    },
     classifiers=[
         'Development Status :: 4 - Beta',
         'Environment :: Web Environment',