Removed very old versions of belief code
Clarified that we need a C++11 compiler

In particular, g++-4.8 with libstdc++-4.8 isn't good enough (it doesn't
support <regex>), but g++-4.9 or clang 3.3+ will do (the latter with
libc++ or libstdc++-4.9).
Added postgresql database support for CLI tools
Merge branch 'master' of github.com:erisproject/creativity