Add basic CONTRIBUTING.md (flutter#173)

CONTRIBUTING.md

@@ -0,0 +1,85 @@
+Contributing to Flutter
+=======================
+
+[![Build Status](https://travis-ci.org/flutter/plugins.svg)](https://travis-ci.org/flutter/plugins)
+
+_See also: [Flutter's code of conduct](https://flutter.io/design-principles/#code-of-conduct)_
+
+Things you will need
+--------------------
+
+ * Linux, Mac OS X, or Windows.
+ * git (used for source version control).
+ * An ssh client (used to authenticate with GitHub).
+
+Getting the code and configuring your environment
+-------------------------------------------------
+
+ * Ensure all the dependencies described in the previous section are installed.
+ * Fork `https://github.com/flutter/plugins` into your own GitHub account. If
+   you already have a fork, and are now installing a development environment on
+   a new machine, make sure you've updated your fork so that you don't use stale
+   configuration options from long ago.
+ * If you haven't configured your machine with an SSH key that's known to github, then
+   follow [GitHub's directions](https://help.github.com/articles/generating-ssh-keys/)
+   to generate an SSH key.
+ * `git clone git@github.com:<your_name_here>/plugins.git`
+ * `cd plugins`
+ * `git remote add upstream git@github.com:flutter/plugins.git` (So that you
+   fetch from the master repository, not your clone, when running `git fetch`
+   et al.)
+
+Running the examples
+--------------------
+
+To run an example with a prebuilt binary from the cloud, switch to that
+example's directory, run `pub get` to make sure its dependencies have been
+downloaded, and use `flutter run`. Make sure you have a device connected over
+USB and debugging enabled on that device.
+
+ * `cd packages/battery/example`
+ * `flutter run`
+
+Contributing code
+-----------------
+
+We gladly accept contributions via GitHub pull requests.
+
+Please peruse our
+[style guide](https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo) and
+[design principles](https://flutter.io/design-principles/) before
+working on anything non-trivial. These guidelines are intended to
+keep the code consistent and avoid common pitfalls.
+
+To start working on a patch:
+
+ * `git fetch upstream`
+ * `git checkout upstream/master -b <name_of_your_branch>`
+ * Hack away.
+ * `git commit -a -m "<your informative commit message>"`
+ * `git push origin <name_of_your_branch>`
+
+To send us a pull request:
+
+* `git pull-request` (if you are using [Hub](http://github.com/github/hub/)) or
+  go to `https://github.com/flutter/plugins` and click the
+  "Compare & pull request" button
+
+Please make sure all your checkins have detailed commit messages explaining the patch.
+
+Once you've gotten an LGTM from a project maintainer and once your PR has received
+the green light from all our automated testing (Travis, Appveyor, etc), submit your
+changes to the `master` branch using one of the following methods:
+
+* Wait for one of the project maintainers to submit it for you.
+* Click the green "Merge pull request" button on the GitHub UI of your pull
+  request (requires commit access).
+
+You must complete the
+[Contributor License Agreement](https://cla.developers.google.com/clas).
+You can do this online, and it only takes a minute.
+If you've never submitted code before, you must add your (or your
+organization's) name and contact info to the [AUTHORS](AUTHORS) file.
+
+We grant commit access to people who have gained our trust and demonstrated
+a commitment to Flutter.