Update UserBattleStatus.h

[ 39%] Building CXX object src/model/CMakeFiles/model.dir/UserBattleStatus.cpp.o
/home/trading/Downloads/flobby/flobby/src/model/UserBattleStatus.cpp: In member function ‘void UserBattleStatus::team(int)’:
/home/trading/Downloads/flobby/flobby/src/model/UserBattleStatus.cpp:37:36: error: ‘assert’ was not declared in this scope
/home/trading/Downloads/flobby/flobby/src/model/UserBattleStatus.cpp: In member function ‘void UserBattleStatus::allyTeam(int)’:
/home/trading/Downloads/flobby/flobby/src/model/UserBattleStatus.cpp:50:36: error: ‘assert’ was not declared in this scope
/home/trading/Downloads/flobby/flobby/src/model/UserBattleStatus.cpp: In member function ‘void UserBattleStatus::sync(int)’:
/home/trading/Downloads/flobby/flobby/src/model/UserBattleStatus.cpp:85:34: error: ‘assert’ was not declared in this scope
/home/trading/Downloads/flobby/flobby/src/model/UserBattleStatus.cpp: In member function ‘void UserBattleStatus::side(int)’:
/home/trading/Downloads/flobby/flobby/src/model/UserBattleStatus.cpp:98:36: error: ‘assert’ was not declared in this scope
make[2]: *** [src/model/CMakeFiles/model.dir/UserBattleStatus.cpp.o] Error 1
make[1]: *** [src/model/CMakeFiles/model.dir/all] Error 2
make: *** [all] Error 2