v15: Allow Users To save segments as 'shared' or 'personal'

[#1]

In Discover, we can save segments in personal or shared folders. This helps keep the list of segments manageable. This same capability will be even more useful in v15, since many, many more people have access to Site Catalyst than Discover so the list of available segments will be that much longer if we don't have an option to save as 'personal'.

[#2]

I have dozens of segments created in DW and Discover.  I was really disappointed when we implemented v15 to find that there was no way to share these existing segments with my Site Catalyst users.  It's a significant waste of effort that each user has to re-create core business segments which already exist.