Add changelog & contributing docs

[sum01]

We should consider making a CHANGELOG.md and CONTRIBUTING.md. The changelog should be easy, as we can fill it will all the news posts from the site. I might push that myself sometime soon.

The contributing.md should have stylistic standards for everyone who submits code to go by, such as using XYZ beautifier, with X spaces (or tabs, whatever), and explain the preferred git workflow. @xCoreDev might need to make some of those decisions, since he's done the majority of the C++ stuff.

But if it's up to vote, mine goes to the uncrustify beautifier, and tabs with tabsize 2 😄

[sum01]

http://keepachangelog.com has good guidelines on changelogs. https://github.com/blog/1184-contributing-guidelines has examples of a contributing file.

[cryptokat]

beautifier

How about creating an .editorconfig file? Editorconfig is cross-platform and cross-editor. http://editorconfig.org/ https://gist.github.com/buoto/7e2cff6c17c108658fc751df845b1040