Mentor Sourcery 2014.05

I updated the Linux portion of the RIOT wiki[1] to reflect the newest release of Sourcery. I chose to leave the Windows subsection as is as I was unsure if the Linaro toolchain was still recommended on that platform for some reason. If someone is interested, there is a link for both a tarball[2] and installer[3] version for Windows.

There is also a landing page with links to each version and the toolchain source.[4]