CMakeLists: CMAKE_CXX_STANDARD to fix compilation error

[msenel1978]

Without this fix, I am getting msenel@MACC02CJ3J6LVDL build % make Scanning dependencies of target DataTable [ 33%] Building CXX object CMakeFiles/DataTable.dir/src/DataTable/DataTable.cc.o warning: unknown warning option '-Wno-psabi' [-Wunknown-warning-option] In file included from /Users/msenel/Documents/workspace/DataTables2/src/DataTable/DataTable.cc:1: /Users/msenel/Documents/workspace/DataTables2/include/DataTable/DataTable.hpp:81:35: warning: in-class initialization of non-static data member is a C++11 extension [-Wc++11-extensions] std::string* _headers = 0; ^ /Users/msenel/Documents/workspace/DataTables2/include/DataTable/DataTable.hpp:82:28: warning: in-class initialization of non-static data member is a C++11 extension [-Wc++11-extensions] double** _data = 0; ^ /Users/msenel/Documents/workspace/DataTables2/include/DataTable/DataTable.hpp:83:23: warning: in-class initialization of non-static data member is a C++11 extension [-Wc++11-extensions] int _cols = 0; ^ /Users/msenel/Documents/workspace/DataTables2/include/DataTable/DataTable.hpp:84:23: warning: in-class initialization of non-static data member is a C++11 extension [-Wc++11-extensions] int _rows = 0; ^ /Users/msenel/Documents/workspace/DataTables2/include/DataTable/DataTable.hpp:85:35: warning: in-class initialization of non-static data member is a C++11 extension [-Wc++11-extensions] std::string _response = ""; ^ /Users/msenel/Documents/workspace/DataTables2/include/DataTable/DataTable.hpp:86:34: warning: in-class initialization of non-static data member is a C++11 extension [-Wc++11-extensions] int _response_column = 0; ^ /Users/msenel/Documents/workspace/DataTables2/include/DataTable/DataTable.hpp:87:31: warning: in-class initialization of non-static data member is a C++11 extension [-Wc++11-extensions] bool _data_loaded = false; ^ /Users/msenel/Documents/workspace/DataTables2/include/DataTable/DataTable.hpp:88:31: warning: in-class initialization of non-static data member is a C++11 extension [-Wc++11-extensions] bool _has_headers = false; ^ /Users/msenel/Documents/workspace/DataTables2/include/DataTable/DataTable.hpp:78:45: error: expected ';' after return statement int* shape() { return new int[2] { _rows, _cols }; } ^ ; /Users/msenel/Documents/workspace/DataTables2/src/DataTable/DataTable.cc:185:13: warning: 'auto' type specifier is a C++11 extension [-Wc++11-extensions] for(auto it = lines.begin(); it != lines.end(); it++) ^ /Users/msenel/Documents/workspace/DataTables2/src/DataTable/DataTable.cc:562:32: error: expected ')' drop_columns(new int[1]{column}, 1); ^ /Users/msenel/Documents/workspace/DataTables2/src/DataTable/DataTable.cc:562:21: note: to match this '(' drop_columns(new int[1]{column}, 1); ^ /Users/msenel/Documents/workspace/DataTables2/src/DataTable/DataTable.cc:567:40: error: expected ')' drop_columns(new std::string[1]{column}, 1); ^ /Users/msenel/Documents/workspace/DataTables2/src/DataTable/DataTable.cc:567:21: note: to match this '(' drop_columns(new std::string[1]{column}, 1); ^ 10 warnings and 3 errors generated. make[2]: *** [CMakeFiles/DataTable.dir/src/DataTable/DataTable.cc.o] Error 1 make[1]: *** [CMakeFiles/DataTable.dir/all] Error 2 make: *** [all] Error 2