add escaping of shell parameters
remove --insecure cmd option, but allow to read it from config
no stacktrace for in normal usage mode
Merge branch 'master' into review_140522_remove_insecure

Conflicts:
	lib/suse/connect/zypper.rb
	spec/connect/zyppper_spec.rb
improve code by adding brackets
Merge pull request #79 from SUSE/review_140522_remove_insecure

[Review] Request from 'digitaltom' @ 'SUSE/connect/review_140522_remove_insecure'