Use -std=cxx11 if the compiler supports it

Change-Id: I595ffc7413dc9fe387e175ebf4def4bd00ae9f01
Reviewed-on: http://review.couchbase.org/29978
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Fixup spelling of "unrecognized" ;-)

Change-Id: I27fa5f48bcaa0ee363f5ff1119c6a73b55f81226