[MOD] attempt to boostrapify and simplify the installer. Lots of layout related changes, trying to make the messy code structure easier to read. More cleanup will follow if no objections.

git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@49550 b456876b-0849-0410-b77d-98878d47e9d5