Monitoring plugin will fail with IPv6 addresses

[gbehrmann]

The parsing of the summary parameter will fail for IPv6 addresses: IPv6 addresses use colons, which you already use as a delimiter in that property.

[ivukotic]

I agree. It is done in this way in order to be compatible with the native xrootd monitor. While it will not make us any problem (we have just one collector and that never changed), I will ask Andy to correct this in xrootd protocol and than I'll correct this one.