Rename class 'Utils'

[ljacqu]

Rename the class 'Utils' to be a bit more descriptive. The initial intention was that it is an internal class to ConfigMe, but the file creation thing is useful and should be OK to call, hence the need for a better name. Additionally, util classes that are actually meant to be used only internally should be moved into a new package "internal".

To do

• Rename Utils to FileUtils
• Move StreamUtils and PathUtils from ch.jalu.configme.utils to a new package ch.jalu.configme.internal
  • Same for the associated test classes