GUI-1206: Buckets landing page and bucket contents page

Implements https://eucalyptus.atlassian.net/browse/GUI-1206

Known issue:
The initial sort key isn't working on the buckets landing page and contents page.  Will continue to investigate, but want to open this pull request sooner rather than later for initial UX review and to transition to the detail pages (GUI-1207)
yep, will refactor that in GUI-1207