Add --with-short-names option

This allows linking as "kctx" and "kns" to prevent overlap with kubectl Tab
completion when user hits `ku<Tab>`. Fixes #3.

Also fixed variables KUBECTX and PREV leaking to zsh shell once the _kubectx
function is invoked.

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

completion/kubectx.bash

@@ -5,4 +5,4 @@ _kube_contexts()
   COMPREPLY=( $(compgen -W "- $(kubectl config get-contexts --output='name')" -- $curr_arg ) );
 }
 
-complete -F _kube_contexts kubectx
+complete -F _kube_contexts kubectx kctx

completion/kubectx.zsh

@@ -1,10 +1,10 @@
-#compdef kubectx
+#compdef kubectx kctx=kubectx
 
-KUBECTX="${HOME}/.kube/kubectx"
+local KUBECTX="${HOME}/.kube/kubectx"
 PREV=""
 if [ -f "$KUBECTX" ]; then
     # show '-' only if there's a saved previous context
-    PREV=$(cat "${KUBECTX}")
+    local PREV=$(cat "${KUBECTX}")
     _arguments "1: :((-\:Back\ to\ ${PREV} \
         $(kubectl config get-contexts --output='name')))"
 else

completion/kubens.bash

@@ -5,4 +5,4 @@ _kube_namespaces()
   COMPREPLY=( $(compgen -W "- $(kubectl get namespaces -o=jsonpath='{range .items[*].metadata.name}{@}{"\n"}{end}')" -- $curr_arg ) );
 }
 
-complete -F _kube_namespaces kubens
+complete -F _kube_namespaces kubens kns

completion/kubens.zsh

@@ -1,2 +1,2 @@
-#compdef kubens
+#compdef kubens kns=kubens
 _arguments "1: :(- $(kubectl get namespaces -o=jsonpath='{range .items[*].metadata.name}{@}{"\n"}{end}'))"