Allow files

In FileBrowser now allowed upload files (not only images)

Bug fix and imruves

• Fixed copy/paste image fragment in editor
• Upload file or drag and drop file (not image) will call inserting A element instead IMG. For images will be inserted IMG element
• Added File button
• Fix bug in sticky plugin
• All filebrowser methods return promise
• Fix bug in context menu
• Fix bug in Tooltip and fix bug with context menu
• Fix caseinsensetive in events
• Fixed #28
• Fixed #29
• Fixed #30
• Fix scroll bug in source mode