Remove unused test Ractive-legacy.js

The test file links to the top-level lib folder instead, so this file is not
used.
Update Ractive-legacy.js to v0.3.8

Taken from RactiveJS/Ractive commit
198aca8bf08e36742421c14ad73a9fe69572b830
Fix clone target directory in the instructions
Merge pull request #1 from lluchs/tweaks

Some improvements