Use stable version of H2 (1.3.171)
Remove downloading methods from FileUtils

They are not needed anymore; BukkitDev disallows downloading from
external sources.
Move loadLibrary() calls from static initializers to LogItCore.start()

God, I'm so undecided.
Remove leftover imports from FileUtils
Update README.md

It should include list of optional libraries (each with its purpose
explained) and updated installation steps, as LogIt from now on will
be released in a ZIP.