Start complete pending experiments

[Endran]

As a user I want start complete pending experiments, so that I can start tracking added value

Description

Directly from the homepage pending experiments must be startable. Also from the experiment details screen it must be possible to start pending experiments.

Scope

Front end and backend.

Acceptance Criteria

Directly from the homepage complete pending experiments must be startable.
Incomplete pending experiments must be not startable.
From the experiment details screen it must also be possible to start pending complete experiments.