Clean environment when closing

[elinw]

The app pushes a number of values for paths into the environment ...when shiny closes they should be deleted.

[elinw]

https://stackoverflow.com/questions/23276491/how-to-implement-a-cleanup-routine-in-r-shiny and the links in some of the answers give guidance on how to do this.

[elinw]

@yuiken Do you want to take this on?

[elinw]

#112 Sort of related?

[Yuiken]

ok