Add a code of conduct and call out in README

This is the CoC from http://contributor-covenant.org.

CODE_OF_CONDUCT.md

@@ -0,0 +1,41 @@
+# Contributor Code of Conduct
+
+As contributors and maintainers of this project, and in the interest of
+fostering an open and welcoming community, we pledge to respect all people who
+contribute through reporting issues, posting feature requests, updating
+documentation, submitting pull requests or patches, and other activities.
+
+We are committed to making participation in this project a harassment-free
+experience for everyone, regardless of level of experience, gender, gender
+identity and expression, sexual orientation, disability, personal appearance,
+body size, race, ethnicity, age, religion, or nationality.
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery
+* Personal attacks
+* Trolling or insulting/derogatory comments
+* Public or private harassment
+* Publishing other's private information, such as physical or electronic
+  addresses, without explicit permission
+* Other unethical or unprofessional conduct.
+
+Project maintainers have the right and responsibility to remove, edit, or reject
+comments, commits, code, wiki edits, issues, and other contributions that are
+not aligned to this Code of Conduct. By adopting this Code of Conduct, project
+maintainers commit themselves to fairly and consistently applying these
+principles to every aspect of managing this project. Project maintainers who do
+not follow or enforce the Code of Conduct may be permanently removed from the
+project team.
+
+This code of conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community.
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by opening an issue or contacting one or more of the project
+maintainers.
+
+This Code of Conduct is adapted from the
+[Contributor Covenant](http://contributor-covenant.org), version 1.2.0,
+available at [http://contributor- covenant.org/version/1/2/0/](http
+://contributor-covenant.org/version/1/2/0/)

README.md

@@ -5,6 +5,15 @@ Quick way to get the platform for joind.in development set up
 
 This repository provides a vagrant virtual machine so you can start contributing quickly. Joind.in is a big project, so there a few parts involved.
 
+### Welcome
+
+Joind.in welcomes all contributors regardless of your ability or experience. We especially welcome
+you if you are new to Open Source development and will provide a helping hand. To ensure that
+everyone understands what we expect from our community, our projects have a [Contributor Code of
+Conduct](CODE_OF_CONDUCT.md) and by participating in the development of joind.in you agree to abide
+by its terms.
+
+
 ## Getting Started
 1. Install requirements. (Note: these are not required by joind.in itself, but are required for this quick start guide.)
    - VirtualBox and the VirtualBox Extension Pack (https://www.virtualbox.org/) (version 4.0 or later)