Adapt the 'Recent posts' panel to multi-blog feature

This task is part of the blog application improvement proposal: http://design.xwiki.org/xwiki/bin/view/Proposal/BlogImprovemultiblogsupport

The behavior of the recent posts panel will change depending on the context where the panel is displayed. For each context we define the behavior as follows:

• aBlog.aPost or aBlog.WebHome
  • List all recent posts in blog space aBlog
• aCategorySpace.aCategory
  • List all recent posts that are in that category aCategorySpace.aCategory
• aCategorySpace.WebHome
  • List all recent posts that are in a category aCategorySpace.%
• Blog.aPost or Blog.WebHome
  • List all recent posts that are in a category Blog.% or in space Blog (or in any space that use the Blog space for category)