Merge pull request #2788 from Who828/handle_sigints_for_workers

Gracefully shutdown workers/threads in case of SIGINT
Update thor to
https://github.com/erikhuda/thor/commit/fdb8028dfb85b58861453d524eba6999d9220504
Use the thor debug option instead of the environment variable

Fixes #2790
Merge pull request #2794 from rafaelfranca/rm-debug-config

Use the thor debug option instead of the environment variable
Change build badge to the master branch.

Also change the hostname to what's recommended in http://about.travis-ci.org/docs/user/status-images/ (they all redirect to the same place, but this is cleaner).

[ci skip]
refocus contributing on what can be done
Fix Rubygems integration with 1.8.0-1.8.19
Add Ruby 2.1.0 to .travis.yml
Merge pull request #2801 from salimane/pr_ruby_2_1_0

Add Ruby 2.1.0 to .travis.yml
switch to rubygems 2.2 branch
note room name
Ruby 2.1 actually ships with Rubygems 2.2.0
rubygems 1.8.29
rubygems 2.0.14
rubygems 2.2.0
update document link version in DEVELOPMENT.md
Merge pull request #2803 from loveky/master

update document link version in DEVELOPMENT.md
note code of conduct in contributing.md
rubygems 2.2.1
rubygems 2 still supports 1.8!