Delete $logRecords argument from Span::finish()

[ellisv]

Also see #53

This $logRecords is not documented by any PHP docs but I imply that implementation suppose to call log() before flushing.

Having that means

• flush() is responsible for two things
• this feature is specific to this library as it is not found in any other opentracing library

Instead promote usage of

$span->log([...]);
$span->finish();

[jcchavezs]

Ping @beberlei @tedsuo @yurishkuro

[yurishkuro]

+1

logs-on-finish were originally added to Go API to handle offline processing cases. Specifically, the logRecord contains the timestamp, while the standard log() methods don't allow timestamp (since Go doesn't support method overloading). In languages that allow overloading or optional arguments, I don't see a reason for having bulk logs-on-finish.

[jcchavezs]

+1 Ping @beberlei