Numeric Fixes

Big thanks to @ericzc0423, @flintforge, @geertn, @marji, and @jage, for their help.

This fixes two small issues with numeric handling:

• get_data now ensures that all (expected) numeric data points default to zero in the event of an empty string (non-numeric addition); and
• It is no longer assumed that every BACKEND has at least one server associated with it (divide-by-zero error).

Initial release

First release of the haproxyng munin plugin.