Merge pull request #1 from charlieg/gh-pages

publishing via pull request to test instructions
added detailed instructions for how to contribute new content to the site
added post for Weka
added post for OpenRefine
added post for SciPy
added post for NumPy
added Events page
Incremental changes towards design refresh
changed color of Twitter & RSS buttons… trying to trigger gh-pages rebuild
Updated license info
Switched to an imageless and responsive "Fork me on GitHub" ribbon, based on: http://codepo8.github.io/css-fork-on-github-ribbon/
Fixed responsive padding in footer
Playing with responsive padding a bit more.
More CSS tweaks...
Last few CSS tweaks for refresh...
fixed minor typo
Added Big Data for Executives to Events page
added photo & slides for Big Data for Executives conference
Update 2014-03-28-altamira-lumify.markdown
organization of tools list