Feature/new status

Removed "running" as JobOffer state. #348 
Employers are now able to create JobOffers before they get activated. These JobOffers are not viewable for students until the employer gets activated. #392 

I'm very sorry that it took so long but there were a lot of replacements to do and failures in the job offer work flow... 

PS: After a faulty login a flash message is displayed #399.