add a CONTRIBUTING.md file

add a CONTRIBUTING.md file, copied verbatim from the "Pull Requests" section in README.md
Update LICENSE
Unignore "packages/*/build" in VisualStudio.gitignore.
Merge pull request #694 from anurse/patch-1

Unignore "packages/*/build" in VisualStudio.gitignore.
Adding CocoaPods to gitignore
Merge remote-tracking branch 'matzew/master' (pull request #418)
Remove Podfile.lock from Objective-C ignores

Per discussion in #148.
Merge pull request #493 from strugee/master

This repository didn't have a CONTRIBUTING.md file. Now it does.
Merge pull request #576 from nysa/master

Ignore Vim untitled and unsaved buffer swapfiles
ignore kernel object files
added secret_token.rb

I added secret_token.rb file to the gitignore as there are public repos sharing it.
Merge pull request #714 from mattjeffery/ignore_kernel_objects

Ignore kernel object files
Merge pull request #735 from aldo-roman/patch-1

added secret_token.rb