Add support for OPTIONS method

This method simply sends the support methods, content types, etc.
Currently all methods that are supported in server.cpp (not commented out)
are the support methods. Once we implement other functionality,
options.cpp will need to be updated.

Tested using curl and works as expected.
Any file that is imported by another file (such as how server.cpp imports "options.h") needs to be listed as a dependency for that file within the Makefile.
ie. this line should now be `server.o: ConnObj.o response.o putResponse.o options.o` (if it has other new dependencies that I missed they should be listed here too)