Add delte functionality

Adding a option to delete different aspects of the database via an api. Such that at the start of a LANcie year the database can be emptied via the admin panel.

More web tab functionality

Merge pull request #41 from AreaFiftyLAN/feature-web_tab

Add web tab to admin page

Polymer 2.0

Polymer 2.0 Upgrade (#35)

* Initial upgrade attempt

* Remove old dependencies

* Fix a bunch of linter errors and imports

* Dynamic column creation for vaadin grid

* Partially fix dynamic column creation

* Fix columnrenderer, apply material design and add sorting

* Add sorting icon and selection column

* Fix webcomponents javascript and consumption dropdown

* Fix build

* Update build.sh for new build process

* Clean dependencies and structured root directory

* Add last style fixes and hide empty table