Web landing page for new OpenStack Security Guide.
- Currently only includes link to epub file.
- Will update / uncomment when pdf / lulu is setup.

Fixes: bug #1196797
Change-Id: Ib9f82e043a462020193d66b3c77f93baeda3e14f
Merge "Web landing page for new OpenStack Security Guide. - Currently only includes link to epub file. - Will update / uncomment when pdf / lulu is setup."