Example has minor issues

We probably should accept an IP address on the command line, and default to localhost. It is hardcoded as an ip for a vagrant cluster now.

Also Brett Lawson saw this on some centos 7 machine:

[centos@ip-172-31-44-24 txnexample]$ make
Scanning dependencies of target game_server
[100%] Building CXX object CMakeFiles/game_server.dir/game_server.o
In file included from /usr/include/c++/4.8.2/mutex:35:0,
from /usr/include/couchbase/client/cluster.hxx:21,
from /home/centos/txnexample/game_server.cxx:4:
/usr/include/c+/4.8.2/bits/c0x_warning.h:32:2: error: #error This file requires compiler and library support for the ISO C+ 2011 standard. This support is currently experimental, and must be enabled with the -std=c+11 or -std=gnu+11 compiler options.
#error This file requires compiler and library support for the \
^
In file included from /usr/include/couchbase/client/collection.hxx:21:0,
from /usr/include/couchbase/transactions/attempt_context.hxx:24,
from /usr/include/couchbase/transactions.hxx:24,
from /home/centos/txnexample/game_server.cxx:5:
/usr/include/couchbase/client/mutate_in_spec.hxx:21:29: fatal error: nlohmann/json.hpp: No such file or directory
#include <nlohmann/json.hpp>
^
compilation terminated.
make[2]: *** [CMakeFiles/game_server.dir/game_server.o] Error 1
make[1]: *** [CMakeFiles/game_server.dir/all] Error 2
make: *** [all] Error 2