Update fatfree app and test to support namespace F3 update made to fatfree-core in #112.

[sgpinkus]

All references to fatfree-core now prefixed with vendor namespace "F3". Please refer to bcosca/fatfree-core#110.

Note fatfree-core directory has moved from lib to f3, just because it just worked with the existing f3 autoloader. Submodule references also needs to be updated, but need a commit to reference before that can be done.

[sgpinkus]

BTW to test this:

git clone -b namespace-fatfree-core https://github.com/sam-at-github/fatfree
cd fatfree/
git rm -rf f3/
git submodule add -b namespace-fatfree https://github.com/sam-at-github/fatfree-core f3
php index.php # or setup HTTP server to serve cwd.

[ikkez]

solved in v4 test app