[FIX] Crawler should handle white space in path as like browser does
[IMP] improve backend views

[IMP] Apply PEP8
[imp] website_slides: added promote functionality for slides in slide grid view
[IMP] usability: backend view + add channel setting button in frontend
[IMP]: improve promote button in slide-grid layout
[IMP] Set page titel for channels and set required field based on slide type
[IMP]: small type improvements
[imp] website_slides: optimize image height problem in related slides list in embed view