Ticket 489: selection box when no records were selected

When no records were selected, a dialog is opened with a slider allowing people to indicate how many records they want to include for metrics, citation helper, word cloud, etc etc etc. Every 'service' has a number of maximum records allowed. If the number of results is less than this maximum, the slider opens set on the results number by default. The main changes are in the RecordListManager where a function 'set_records' was introduced, which is now called rather than e.g. calling the 'metrics' function directly. If records were selected, the actual function (e.g. 'metrics') is immediately called, otherwise the dialog is opened. The dialog box depends on jQuery UI widgets ('dialog', 'draggable' and 'slider'). To make the number of results easily available to the Javascript in the ResultsListManager, this value was stored as the initial value of the slider in the search results template. To give the dialog more flexibility in placement, additional jQuery UI widgets are needed ('mouse' and 'position') which seemed to create conflicts with bootstrap.