update to latest cpp-driver
As of time of creating this issue, the latest release was 2.15.3. Before doing any work, please take a look at the state of the project: https://github.com/datastax/cpp-driver. There's a worrisome note about the c/c++ driver being in maintenance mode. Does it mean that Cassandra no longer cares about C++? Are there better alternatives? Maybe latest Cassandra supports C++ out of the box?
Also, the ARM Section 3.5.3 has outdated installation instructions that mention 2016. If they're still correct, we should bump the date. Also, update it as necessary.