Move getCanonicalFile/Path into FileUtils
Fix: Filesystem not strict case sensitive.

Mac file system does not properly distiguish between upper and lower case characters.

Inside java files with case differences are considered to be not equal. This causes trouble during build preparation (copy files step).

In order to avoid such trouble we use only canonical files.
[refactoring] cleanups

import static in order to improve readability.

Remove unnecessary getAbsoluteFile calls.