Merge pull request #2166 from obscuren/contrib

CONTRIBUTING: Added a feature section

CONTRIBUTING.md

+## Can I have feature X
+
+Before you do a feature request please check and make sure that it isn't possible
+through some other means. The JavaScript enabled console is a powerful feature
+in the right hands. Please check our [Bitchin' tricks](https://github.com/ethereum/go-ethereum/wiki/bitchin-tricks) wiki page for more info
+and help.
+
+## Contributing
+
 If you'd like to contribute to go-ethereum please fork, fix, commit and
 send a pull request. Commits who do not comply with the coding standards
 are ignored (use gofmt!). If you send pull requests make absolute sure that you