Fix no reader when tryied to read empty file, fixed import when some request answers with err 500, normalized maxSize according to doc

[sbengo]

Fix

• Fix no reader when trying to read empty or non file. Fix [Bug] Collector doesn't recreate the reader after empty file rotation #25
• Fix no import if some http request returns some error
• Normalise maxSize packets according to sftp package. This is a try to solve Error on open file: failed to send packet header: EOF #20