Allow for multipage scanning and prevent conflict in scanfile names.

[noci2012]

Is your feature request related to a problem? Please describe. A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]

Unable to scan multipage documents, .pdf seems a better fit. Some extra options are needed for scan image. (for HP also a --source needs to be specified). sudo is not needed

Describe the solution you'd like A clear and concise description of what you want to happen. See pull-req. #28, #29, #30.

[noci2012]

Also this show that for some scanners a source needs to be defined as well (for HP: ADF or Flatbed) A nice addition could be to also limit the number of pages to be scanned.