Move GetConfigPath to GetAppPath (applications directory)

BUG: XWALK-2672

Change-Id: Iee497d8f5744b1d8c4533fe7f6009040b0bcf826
Signed-off-by: Sabera Djelti (sdi2) <sabera.djelti@open.eurogiciel.org>
1) it should not be before the xwalk_paths.h
2) it's tizen-specific, right? #if defined(OS_TIZEN) ?