Refactor uk-benefits-abroad to use #next_node_if
Allow overriding of entire label for VariableMatches predicate
Better labels on transitions
Include first line of body on outcome nodes

if there's no title defined for the outcome
Improve graphviz output

- colour nodes
- labels for edges
Make intention of label generation clearer

if there are multiple matches wrap the list of them in braces to make it look more like a
mathematical set.
Use instance variables/accessors consistently
Merge pull request #916 from alphagov/uk-benefits-abroad

Uk benefits abroad