Upgrade to Maven Resources plugin version 2.6

Release Notes - Maven 2.x Resources Plugin - Version 2.6


** Bug
   * [MRESOURCES-111] - escapeWindowsPath doesn't work when applying properties
   * [MRESOURCES-131] - Maven resources plugin does not honour
maven.test.skip  flag
   * [MRESOURCES-141] - Filtering doesn't work when there is an odd
number of @ in the resource
   * [MRESOURCES-166] - Escaping on a line suppresses filtering for
the rest of the token/line

** Improvement
   * [MRESOURCES-140] - Plugin shows always '[debug] execute
contextualize' despite the logging level
   * [MRESOURCES-148] - Turn Off '@' Escape Filtering
   * [MRESOURCES-161] - Some incorrect HTML in the description of the
delimiters parameter

** Task
   * [MRESOURCES-139] - misspelling in documentation: </inclues>
   * [MRESOURCES-167] - use new maven plugins annotations.