Added the IDE category and Eclipse Luna framework.

Hi,

this is the first pass, and isn't ready to merge yet.

To download Eclipse, we use a direct link to file which redirects to the best mirror. This link is accessible from the right sidebar at https://www.eclipse.org/downloads/download.php?file=/technology/epp/downloads/release/luna/R/eclipse-standard-luna-R-linux-gtk-x86_64.tar.gz and I think is unlikely to change, so it's safe to hard-code. The MD5 is fetched similarly. Since we don't need to parse anything, I just use the first hook (download_provider_page) to do everything.

This works properly as far as I can tell. What is missing:

* the CLI status indicator doesn't change from 0%. Although for me this doesn't work for Eclipse-ADT either. Status updates are sent though (this is handled in DownloadCenter).
* there are no tests (yet)
* there is no support for 32-bit (yet)

I'll be away for a few days before I can continue working on this. Comments welcome!
That's the one I'm the more unsure of. As you have to hardcode the version in it and hope that we'll have mirror for i386/amd64 and that the file stays at the same place forever.

I would really prefer that we go on parsing the webpage as for android. Basing on https://www.eclipse.org/downloads/?osType=linux, grabbing there the 32/64 bits version. There is a flag to ensure we don't check for a license, expect_license, and it's off by default.

If the page is broken/change, we can detect that as quickly as if the hierarchy of files changes (which may happen with next eclipse release, as they may change their web page as well).