preparing 0.5.11 release

prepareing 0.5.11-beta3

prepare 0.5.11-beta2

Move the requirement of Unox to the top-level, not being handled by t…

…he unox dependency itself, since the dependency management is not suitable for sub-dependencies right now. So handle it top-level and require unox only, if it's a mac

try to adjust / fix the test for unox and when it should be called / available or throw exceptions

a more elaborated approach to fix EugenMayer#635

prepare 0.5.10 release

prepare 0.5.10-beta1

preparing 0.5.9

trying to fix travis builds / rspec tests

fix documentation of global image override

add upgrade message