Fix some issues with cat-boot-enum on the first page load

[JoelColledge]

Branches from #12

[tsalzinger]

there actually is a reason why it was done in exactly this way (only initializing at the beginning and then resolving enum values synchronously)

when you use the promises the issue is that the ui begins to 'jump' as they are resolved asynchronously - especially with your changes which empties always selects the first option (which is not good either because that might not be the intended behavior at all times)

in addition there is will be an enum filter in the future and filters in angular can only be synchronous, therefor the promise approach doesn't work there

and as a general rule: please open an issue before investing time into changing something that actually might not even be wanted in such a way, at least then a discussion on a solution can take place before any code is acutually written (which might be wasted effort otherwise)