Reorganise account management

[sebtesobe]

Currently, the management pages are somewhat disorganised in URL and naming (base URL is the specific account):

• /permissions
  • Grant access to views to specific users
  • PermissionManagement.scala + permissions.html
• /permissions/create
  • Add user to which access to views can be granted
  • CreatePermissionForm.scala + permissions/create.html
• /management
  • Manage counterparties
  • Management.scala + management.html
• /views/list
  • Manage permissions on views and add/delete/edit views
  • ViewsOverview.scala + views/list.html
• /settings
  • Manage account settings (currently only the account label)
  • AccountSettings.scala + settings.html

Maybe these URLs (and accordingly named scala snippet files) would be better:

/manage/counterparties
/manage/settings
/manage/views (old ViewsOverview)
/manage/views/users
/manage/views/users/add