avoid occupation detail rendered twice

[myarjunar]

fix #573 Occupation Backbone view model is destroyed in one page refresh cycle. I haven't found that but there is another way to avoid that: by avoiding occupation detail rendered twice. I also found a way to boost the performance of this workflow by replacing ajax request with structured backbone view. I will make a separate PR for that.

587 <- for replacing ajax request

588 <- for destroyed occupation model

[myarjunar]

can we merge this @cchristelis ?

[meomancer]

LGTM