Finilize system info dashboard widget.

git-svn-id: http://svn.code.sf.net/p/openmediavault/code/trunk@1172 3c3d7b80-5828-415e-9f61-280b98178fff
Improve dashboard widgets. Widgets can be defined to be shown after the UI is used the first time or the cookie has been cleared.

git-svn-id: http://svn.code.sf.net/p/openmediavault/code/trunk@1173 3c3d7b80-5828-415e-9f61-280b98178fff