Third patch on the #88217 issue:

- Handles the functionalities of start and close dates through two new functions "decisions_can_vote()" and "decisions_is_open()"
- Prints status messages at the top of the node view to inform the user about quorum/can vote/is open isues
- Adds a theme_decisions_status() function to print status messages such as "This decision is not yet opened."
- Modifies the decisions_view_vote_counts() to print date information; renames the function to theme_decisions_view_header()