Fix zsh issue where array-index starts at zero

This is related to listing kre runtimes and associating with aliases.
Z shell arrays start at one versus Bash which starts at zero (ref. https://blogs.oracle.com/breakdown/entry/arrays_in_zsh).
New behavior is backwards-compatible with Bash, however (*at least from cursory local testing*).

**Note: this error only occurs if at-least one alias is defined (since the affecting loop is not executed when no aliases are defined – ref. [kvm.sh#L357-L360](https://github.com/aspnet/kvm/blob/d2713d5e0c298db5394ae6a9572d43d28125e532/src/kvm.sh#L357-L360).**

#### Current zsh error:
![image](https://cloud.githubusercontent.com/assets/3382469/4423083/ea3360e2-4591-11e4-8652-c12ae705bd7a.png)