Remove redundant items from gitignore
Ignore release files
Rename lightbox.js file to lightbox-phts.js

To show that his is a fork.
Change application name
Merge branch 'master' into dev
Make `.lb-nav` element cached
Refactor image loading

Add possibility to add more album entry types.

Create separate classes AlbumEntryFactory and Img represented an image entry.
Use `load` function to have possibility to have own loader function for each
album entry types.

Move "fit image" related code to a separate function `_fitImage`.
Add classes to previews and container depending on the album entry type
Add experimental support for Youtube embedded videos

Also add a sample style for "youtube" images.