Bump json from 1.7.4 to 1.8.6

[dependabot]

Bumps json from 1.7.4 to 1.8.6.

Changelog

Sourced from json's changelog.

2017-01-13 (1.8.6)

• Be compatible with ancient ruby 1.8 (maybe?)
  2015-09-11 (1.8.5)
• Be compatible with ruby 2.4.0
• There were still some mentions of dual GPL licensing in the source, but JSON
  has just the Ruby license that itself includes an explicit dual-licensing
  clause that allows covered software to be distributed under the terms of
  the Simplified BSD License instead for all ruby versions >= 1.9.3. This is
  however a GPL compatible license according to the Free Software Foundation.
  I changed these mentions to be consistent with the Ruby license setting in
  the gemspec files which were already correct now.
  ---------- (1.8.4) Skipped.
  2015-06-01 (1.8.3)
• Fix potential memory leak, thx to nobu.
  2015-01-08 (1.8.2)
• Some performance improvements by Vipul A M vipulnsward@gmail.com.
• Fix by Jason R. Clark jclark@newrelic.com to avoid mutation of
  JSON.dump_default_options.
• More tests by Michael Mac-Vicar mmacvicar@gmail.com and fixing
  space_before accessor in generator.
• Performance on Jruby improvemed by Ben Browning bbrownin@redhat.com.
• Some fixes to be compatible with the new Ruby 2.2 by Zachary Scott e@zzak.io
  and SHIBATA Hiroshi hsbt@ruby-lang.org.
  2013-05-13 (1.8.1)
• Remove Rubinius exception since transcoding should be working now.
  2013-05-13 (1.8.0)
• Fix flori/json#162 reported by Marc-Andre
  Lafortune github_rocks@marc-andre.ca. Thanks!
• Applied patches by Yui NARUSE naruse@airemix.jp to suppress warning with
  -Wchar-subscripts and better validate UTF-8 strings.
• Applied patch by ginriki@github to remove unnecessary if.
• Add load/dump interface to JSON::GenericObject to make
  serialize :some_attribute, JSON::GenericObject
  work in Rails active models for convenient SomeModel#some_attribute.foo.bar
  access to serialised JSON data.
  2013-02-04 (1.7.7)
• Security fix for JSON create_additions default value and
  JSON::GenericObject. It should not be possible to create additions unless
  explicitely requested by setting the create_additions argument to true or
  using the JSON.load/dump interface. If JSON::GenericObject is supposed to
  be automatically deserialised, this has to be explicitely enabled by
  setting
  JSON::GenericObject.json_creatable = true
  as well.
• Remove useless assert in fbuffer implementation.
• Apply patch attached to https://github.com/flori/json/issues#issue/155
  provided by John Shahid jvshahid@gmail.com, Thx!
• Add license information to rubygems spec data, reported by Jordi Massaguer Pla jmassaguerpla@suse.de.
• Improve documentation, thx to Zachary Scott zachary@zacharyscott.net.
  2012-11-29 (1.7.6)

... (truncated)

Commits

• 7f4cfd8 Try to be compatible with ruby 1.8
• 4cf6c62 Update gemspecs
• 48c5e99 Stop testing on 1.8, it might work though
• 5d46fb9 Travis don't know how to build these rubies
• 7f05140 Fix conversion crash on 1.9
• 2bcacc1 Require ruby version 2.0 or better
• f8e2aa6 Reduce supported ruby versions
• b4eeed1 Test newer rubies
• c7a6e31 Use 2.3.1 for testing
• 953f474 Merge RUBY_INTEGER_UNIFICATION changes
• Additional commits viewable in compare view

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