models: break out of loops

[alrs]

This fixes three spots in the models package where a break was being called from a switch that was inside a for loop, turning it into a no-op. This labels the outer loop so the break will make it out of both the for and the switch.

[zeripath]

mea culpa.

[cornelk]

will an empty case not result in the same result but not require a goto and lable?

[zeripath]

@cornelk compare:

https://play.golang.org/p/TFSvn_2IK6T

with:

https://play.golang.org/p/arHLETHlrm9

or:

https://play.golang.org/p/gi550S1EmOP

[zeripath]

the error came from when during a failed refactor attempt I tried to move this out to a method that returned directly - but didn't I unwind the refactor completely

[lafriks]

Maybe break could be replaced with return true, signingKey, nil. I know it duplicates code but at least label is not needed :)

[zeripath]

make lgtm work