fix ByParent
kernel version - don't show the dash if flavor is empty
Check the command existance prior create and add Unit tests for the case
Merge pull request #552 from dotcloud/548-no_command_panic-fix

- Builder: Check the command existance prior create and add Unit tests for the case
Merge pull request #550 from unclejack/handle-empty-kernel-flavor-without-dash

* Runtime: kernel version - don't show the dash if flavor is empty
Merge pull request #539 from justone/fix-byparent

- Images: fix ByParent function
fix run no parameter
Merge branch 'master' into remote-api
display id on run -s stdin