[installer] [host] fix unterminated sed command
[installer][host] we need the zlib linker flag on OSX
[installer][host] fix switching after download. fix file selection. fix race condition.
Merge pull request #7 from srmo/fix-use-local-image

[installer][host] fix switching after download. fix file selection. fix ...
Merge pull request #6 from srmo/fix-zlib-link-osx

[installer][host] we need the zlib linker flag on OSX