Added slider block view for listingblock.

:construction_worker: . :construction: . :construction_worker: 
##### todo
 - [ ] Only register view if ftw.contentpage is installed
 - [ ] Make settings (auto-slide, slide-speed, effect, usw...) configureable in ListingBlock
 - [ ] Update styling
 - [ ] Update readme; add description how this works with ftw.contentpage
 - [ ] Remove debugging stuff from buildout configuration (`development.cfg` and `sources.cfg`)