[Perf] [Bug] Figure out why first fetch during parsing doesn't always give all objects, refactor

[thomassnielsen]

This is a particularly nasty bug that most likely causes most of the current issues of TSNREST, including duplicates. Sometimes when fetching from the local store, there will be some objects that doesn't load, and we have to load them individually later in the parsing process to avoid duplicates. There must be some way to avoid this.

[thomassnielsen]

One of the problems we face is that there may be new objects added to the store during parsing, but that can't account for every time this happens, it's way to often. We may need to go back to parsing on a serial queue though, to avoid these issues entirely.

[thomassnielsen]

I'll be much more comfortable fixing this when we've got tests in place and have refactored more of the related code. It's too volatile right now, and I feel we've gotten new bugs for every one we fix.

[thomassnielsen]

By fixing #40 I think this might be better, if not entirely fixed. Using @synchronized or going to a serial queue might be needed to fix this entirely.