WFLY-2351 Escape servlet exceptions in the error page
- replaces #toLowerCase() with #toLowerCase(Locale),
  #equalsIgnoreCase(String), #compareToIgnoreCase(String),
  or #regionMatches(boolean, int, String, int, int). #toLowerCase()
  without a Locale may lead to unexpected results in JVMs with Turkish
  locale (s. JavaDocs of String#toLowerCase()). Additionally it improves
  performance as #equalsIgnoreCase(), #compareToIgnoreCase() and
  #regionMatches() are faster in comparison to equivalent
  code which uses combination of #toLowerCase() and #equals(),
  #compareTo() or #startWith().
UNDERTOW-116 FileResourceManager should use canonical path
Fix issues with file canonicalization