deps: debug@^0.8.0
update connect to 2.15.0
update history
docs: use SVG badges
docs: add NPM badge
docs: update core contributors
Merge branch '3.5.x' into 3.x
update mkdirp to 0.5.0
update supertest to 0.12.0
tests: add test for app.delete
Value parameter of app.set() is now typed optional mixed
remove deprecation message about passing path as array

backport commit 6b19e3dc0a3b303c541708860a6f9de2ae281b9d
Add standard deprecation utility

 * deprecations ignore when NODE_ENV=test
 * uses node.js util.deprecate
deprecate app.del

closes #2095
deprecate res.json(obj, status)

closes #2106
closes #2107
tests: add test for res.format in route

closes #2016
tests: add more res.jsonp? tests
build: add soft testing on node.js 0.11
support PURGE method
Fix req.next when inside router instance

fixes #2016