Add find file class to search for files

Scan a folder for a file based on file name. First scan the files
in the current path, then search real directories and finally
search symlinks in that order. Goal is to locate important sysfs
files for things like brightness, battery capacity, lun files, etc

This implementation just scans for the brightness file for the LCD

Change-Id: I8ed3e74a2e2851d58b443718b6e92b50a5491f08