Add a tag to/from a filter by simply clicking on them in the project list

[matevz]

In the home view, when clicking on a tag of some project, add that tag to the filter. Or, if the tag is already in the filter, remove it. This also changed behavior so that the project details are shown when you either click on the project title or a screenshot and not on other elements.

[matevz]

Implemented in https://github.com/oasisprotocol/playground/pull/70