Please add std before max() functions

In include/travatar/util.h, max() is used outside of the namespace std.
When I build it, the following error is occured:

In file included from ./../include/travatar/hyper-graph.h:13:0,
                 from hyper-graph.cc:8:
./../include/travatar/util.h: In instantiation of 'int travatar::CheckPtrVector(const std::vector<T*>&, const std::vector<T*>&) [with T = travatar::HyperEdge]':
hyper-graph.cc:148:45:   required from here
./../include/travatar/util.h:254:17: error: 'max' was not declared in this scope, and no declarations were found by argument-dependent lookup at the point of instantiation [-fpermissive]
In file included from /usr/include/c++/4.7/deque:61:0,
                 from /usr/include/c++/4.7/queue:61,
                 from hyper-graph.cc:1:
/usr/include/c++/4.7/bits/stl_algobase.h:254:5: note: 'template<class _Tp, class _Compare> const _Tp& std::max(const _Tp&, const _Tp&, _Compare)' declared here, later in the translation unit

Please use max() with std:: to solve it.