Schema assumptions hard coded into static build step

[almereyda]

As a precursor to #5 one could prepare a more flexible visualisation environment, by refactoring the UI settings from

https://github.com/adadgio/neo4j-js-ng2/blob/da3eda17274951ce4b625dc68ae733222a90fe43/src/assets/neo4j.settings.json.dist#L6-L30

into the frontend for live editing of the desired presets, without having to rebuild the application. These settings represent hard coded assumptions about the expected schema of the database, and may therefore be configured by the end user.

Presets could be stored in LocalStorage, and eventually im- and exported as JSON.

[almereyda]

Further on there are some kind of property templates in

https://github.com/adadgio/neo4j-js-ng2/blob/422aef5d3c1f160d70364e7bb69c2fe4fda4155f/src/app/component/link-edit/link-edit.component.ts#L13

and

https://github.com/adadgio/neo4j-js-ng2/blob/422aef5d3c1f160d70364e7bb69c2fe4fda4155f/src/app/component/node-edit/node-edit.component.ts#L11

which one may wish to build upon.