Remove C++ TR1 stuff which is not support by Apples Clang 5 compiler.

Since GCC 4.4 the used functions are available in the std namespace
anyway.
(reviewed by bernd)


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@11995 2fb0f335-1f38-0410-981e-8018bf24f1b0