Resolve #441: Improve relationship party selection widget

[seav]

Proposed changes in this pull request

• Resolve Improve party selection widget #441:
  • Use Select2 to convert the table of selectable parties used in creating a new tenure relationship into a searchable select box. Select2 was used instead of Selectize that was suggested by @clash99 because Select2 has its CSS and JS files hosted on a CDN. Both support the features that we might want in a party selection widget and it's easy to switch to Selectize if that is desired.
  • Update the SelectPartyWidget widget to output <select> instead of <table>.
  • Update the NewEntityWidget widget to show the "Add party" button as a button instead of as a link, and to make the button text translatable.
  • Update the relationship_add.html template to load Select2 into the party <select> tag, and to make the widget <label>s translatable.
  • Update main.scss to style the updated widgets.
  • Update the widget unit tests.

Screenshots

Default view of the "Add New Relationship" modal showing the Select2 in action.

When the select box is clicked, we get a nice list of parties with their names and types shown. This can be easily updated in the future to include as many party attributes as needed.

Clicking on a party locks that selection in.

Clicking on the "Add party" button allows us to create a new party instead. This is the same as the previous behavior.

When there are more than 5—this is customizable—parties in the project, the Select2 widget displays a search box that can filter the parties that can be selected.

When should this PR be merged

It would be nice if @clash99 can take a look and see if the updated widget is up to the task. Alternatively, this can be merged now and then updated in the future.

Risks

No risks foreseen

Follow up actions

None.

[clash99]

Looks good! I think this is a big improvement. Its very intuitive and I think the search box will help a lot as our party list grows.

I have two small suggestions:

• Add a glyphicon-plus to the add button
• Remove comma after "or"

Otherwise its good to go!

[seav]

Suggestions have been applied: