Methods to check river/bucket existence

* Added utility methods to in the Account service class to aid
in check if a given river or bucket is owned by a given
account
Fix bucket settings display

* Removed the view layout from the list of bucket settings
This should be a client-specific setting; use a client-specific
DB for such config
Use absolute URL for dashboard url

* Relative URLs break the redirection when the application
is installed in a directory relative to the document root