Restores the look-for-Boost step because removing it breaks my build.

(This assumes that I'm supposed to install cyclopts before anything else, yes?)

Restores the step where cyclopts looks for boost. It uses boost in Solver.h and Variable.h, so I'm not sure why the part of the build where cyclopts looks for boost was diabled.


When I built cyclopts : 
``` 
Scanning dependencies of target cyclopts
[ 20%] [ 40%] [ 60%] [ 80%] Building CXX object CMakeFiles/cyclopts.dir/Interface/SolverInterface.cpp.o
[100%] Building CXX object CMakeFiles/cyclopts.dir/Solver/Solver.cpp.o
Building CXX object CMakeFiles/cyclopts.dir/Solver/CBCSolver.cpp.o
Building CXX object CMakeFiles/cyclopts.dir/Utility/Variable.cpp.o
Building CXX object CMakeFiles/cyclopts.dir/Utility/Function.cpp.o
In file included from /Users/khuff/repos/cyclopts/src/Solver/Solver.cpp:1:
/Users/khuff/repos/cyclopts/src/Solver/Solver.h:6:10: fatal error: 'boost/shared_ptr.hpp' file not found
#include <boost/shared_ptr.hpp>
         ^
In file included from /Users/khuff/repos/cyclopts/src/Interface/SolverInterface.cpp:1:
In file included from /Users/khuff/repos/cyclopts/src/Interface/SolverInterface.h:4:
/Users/khuff/repos/cyclopts/src/Solver/Solver.h:6:10: fatal error: 'boost/shared_ptr.hpp' file not found
#include <boost/shared_ptr.hpp>
         ^
In file included from /Users/khuff/repos/cyclopts/src/Utility/Variable.cpp:1:
/Users/khuff/repos/cyclopts/src/Utility/Variable.h:5:10: fatal error: 'boost/shared_ptr.hpp' file not found
#include <boost/shared_ptr.hpp>
         ^
In file included from /Users/khuff/repos/cyclopts/src/Solver/CBCSolver.cpp:1:
In file included from /Users/khuff/repos/cyclopts/src/Solver/CBCSolver.h:4:
In file included from /Users/khuff/repos/cyclopts/src/Utility/SolverTools.h:4:
/Users/khuff/repos/cyclopts/src/Utility/Variable.h:5:10: fatal error: 'boost/shared_ptr.hpp' file not found
#include <boost/shared_ptr.hpp>
         ^
1 error generated.
make[2]: *** [CMakeFiles/cyclopts.dir/Solver/Solver.cpp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
In file included from /Users/khuff/repos/cyclopts/src/Utility/Function.cpp:1:
In file included from /Users/khuff/repos/cyclopts/src/Utility/Function.h:4:
/Users/khuff/repos/cyclopts/src/Utility/Variable.h:5:10: fatal error: 'boost/shared_ptr.hpp' file not found
#include <boost/shared_ptr.hpp>
         ^
1 error generated.
make[2]: *** [CMakeFiles/cyclopts.dir/Interface/SolverInterface.cpp.o] Error 1
1 error generated.
make[2]: *** [CMakeFiles/cyclopts.dir/Utility/Variable.cpp.o] Error 1
1 error generated.
make[2]: *** [CMakeFiles/cyclopts.dir/Utility/Function.cpp.o] Error 1
1 error generated.
make[2]: *** [CMakeFiles/cyclopts.dir/Solver/CBCSolver.cpp.o] Error 1
make[1]: *** [CMakeFiles/cyclopts.dir/all] Error 2
make: *** [all] Error 2
```