Moved construction of view uri and download uri in crud type getters

[maeisabelle]

This is now ready for code review. I moved the construction of view and download uri in the crud type getters.

[grtjn]

Great stuff, clean and simple. I wonder if it makes sense to push this even further down into CrudApi though, to really wrap all knowledge about the api inside those helper libs (which we might eventually expose as shared client libs for vue and react via grove-core-api). @patrickmcelwee and @mariannemyers wdyt?

[grtjn]

I am wondering, it would be even nicer if view/download url knowledge would be pushed down even further, and provided out of the box as part of metadata or such. State should keep a copy of the metadata around, so it can pull view/download uri out of them..

@maeisabelle something you'd like to play with? Would involve touching grove-node a little..