Improve download page on the website

Based on some feedback from a potential customer:

The current download page is great, but only if you want to download GitLab CE. Downloads-ee is hard to fnid

• it should be clear where and how you can download GitLab EE
• we should discourage usage of non-LTS OS, like Ubuntu 15xx (Omnibus only supports LTS releases officially)
• inlude apt-get update as a step
• links should be underlined (see "entire script" link, which looks like the rest of the text) / obvious I did this here: https://gitlab.com/gitlab-com/www-gitlab-com/commit/2f6d399ca7d034c616b78d48526bc5edb9e09304
• (not confirmed by me) In step #2 (closed), it’s sudo dpkg -I gitlab.deb, rather than without sudo
• the links to the packages on packages.gitlab.com now point to only CE, this should be different for EE

I also got feedback on packages.gitlab.com. The customer mentioned that it was very confusing to figure out which package to use and even hit a Rails error.

I also think we should move to a more simpler, white page, with bigger letters and more focus on the content. Maybe we can tackle this all together in a redesign.

Right now I did:

• update the page to have underlines for links in the text https://gitlab.com/gitlab-com/www-gitlab-com/commit/2f6d399ca7d034c616b78d48526bc5edb9e09304
• add a link from /downloads to /downloads-ee: 936e86d2
• link from /features to /downloads-ee: c32c58f5

cc @lukebabb @philcamillo @marin @sytses

Packages.gitlab.com design is not up to us, this is how Packagecloud looks. The rails error was reported and fixed in this issue.

(not confirmed by me), it’s sudo dpkg -I gitlab.deb, rather than without sudo

It should be sudo to keep in line with the previous command.

@JobV thanks for the info, this is really great to know for the redesign. We can definitely factor this into the redesign, just a matter of deciding where this falls in terms of priority. cc @AshleyS

Related to #643 (closed)

I hope we can make some kind of improvement sooner than later. If our paying customers are having trouble finding download/install instructions that's definitely serious. It will give them a bad experience from the start.

Can we add EE easily to the existing page? cc @dblessing @lukebabb @JobV

@JobV what if we feature the existing Download GitLab Enterprise Edition link near the bottom in larger text, a makeshift call-out of sorts, like so (with better spacing and such, of course):

cc @dblessing @AshleyS