FrequencyBasedBootstrapping: FINISHED although SearchTermPosition exits with error

[bolandka]

...and FrequencyBasedBootstrapping cannot do its job properly because of that.

same api call as in infolis/infolis-web#52

http://infolis.gesis.org/infolink/api/execution/8c5c4720-8ff7-11e5-a54f-3fc06a1d5c6e

[Dommii]

Should I change the status of an execution to failed whenever one/more sub executions fail?

[Dommii]

Created a branch where this should be avoided 2eef639