Remove -std=c++11 flag from task 3 compiler args

[egeldenhuys]

Fitchfork is not compiling Task 3 with -std=c++11:

Compile WARNING => Possible compile warnings and/or errors follow, try to get rid of them.
In file included from doubleList.h:116:0,
                 from dListTest.cpp:2:
doubleList.cpp: In copy constructor 'DoubleList<T>::DoubleList(const DoubleList<T>&)':
doubleList.cpp:15:71: warning: delegating constructors only available with -std=c++11 or -std=gnu++11
 DoubleList<T>::DoubleList(const DoubleList<T>& other) : DoubleList<T>(){
                                                                                                                    ^

a3.3

Changed

• Remove -std=c++11 flag when compiling task 3 to match Fitchfork