Bump bundler version

Bump bundler version.
[close #244] Warn when default webserver is used
Merge pull request #255 from heroku/schneems/bundler-161

Bump bundler version
Merge pull request #256 from heroku/schneems/webrick-fuuuuuuuuuuuuuuuuuuuu

[close #244] Warn when default webserver is used
update changelog
bump to v114
set default process types

Fixes case where people have a Procfile, so now they have a `web:` process
Merge pull request #258 from heroku/schneems/fix-procfile-present-on-first-push

set default process types
bump to v115
changelog
Use 1.5.2 as 1.6.1 has a critical bug:

https://github.com/bundler/bundler/issues/2970

.
v116
bump to v116
scope the node path check

Since the anvil service which Travis uses is built using node and
anvil leaks its path into the build enviroment, node is always on the
path, so `node_js_installed?` will always return true. This executes the
direct binary skipping the PATH completely.
add documentation for node_js_installed?
Merge pull request #261 from heroku/node_on_anvil

fix node.js check on anvil
node multibuildpack spec

tests #261
Merge pull request #262 from heroku/schneems/node-multi

node multibuildpack spec
Merge branch 'master' of https://github.com/heroku/heroku-buildpack-ruby

* 'master' of https://github.com/heroku/heroku-buildpack-ruby:
  node multibuildpack spec
  add documentation for node_js_installed?
  scope the node path check
  bump to v116
  v116
  Use 1.5.2 as 1.6.1 has a critical bug:
  changelog
  bump to v115
  set default process types
  bump to v114
  update changelog
  [close #244] Warn when default webserver is used
  Bump bundler version
restore official logic