Hard dependency on InfluxDB - should be loaded on demand

I think it was a bad decision to unconditionally include InfluxDB modules in Smokeping. It's a hard dependency even for people not using it.

SmokePing/lib/Smokeping.pm

Lines 26 to 27 in 64633f4

    
           use InfluxDB::HTTP; 
        
           use InfluxDB::LineProtocol qw(data2line precision=ms);

It even seems that it was optional while being developed. Optional: 45ec481 Mandatory: c4076fc

As this is my first time working with Perl, this is what I found about loading modules on demand: https://stackoverflow.com/a/251786

my $rc = eval
{
  require Term::ReadKey;
  Term::ReadKey->import();
  1;
};

if($rc)
{
  # Term::ReadKey loaded and imported successfully
  ...
}

Although it seems to be recommended to use Try::Tiny.

Indeed that is a bit of a big module for mandatory inclusion ... I agree ... would you care to provide a patch ?
I would suggest to 'require and import' if cfg->{InfluxDB} exists ...

note that the 45ec481 was not actually optional since it used 'use'.

Oh, right, I missed that. It is even the main point of that SO answer.

See #286

Merged, closing now.

	use InfluxDB::HTTP;
	use InfluxDB::LineProtocol qw(data2line precision=ms);