Use asset_id in filename when saving html page for image instead of asset name.
Also removing unused code in html_templates.
Adds support for local assets. Enables upload on the 'add asset'-page.

The page looks like craps atm, but a UI overhaul is coming shortly.
Merge pull request #39 from ASoft-se/fix_asset_image_id

Use asset_id for image html page. fix #30
Bugfix. Resolves issue with invalid syntax for mkdir.
Save a little memory allocation and time by only constructing playlistitem if it is actually needed.
Merge branch 'master' into screenly-ui