(#68) dump scope.compiler.topscope rather than scope

This avoids the information leakage from taking whatever might be in scope of
mcollective::server::config::factsource::yaml, and instead rummages around in
the innards of the compiler to find topscope.

Approach figured out by R.I.Pienaar.

Closes #68
Merge pull request #69 from richardc/bug/master/68

(#68) dump scope.compiler.topscope rather than scope