Add bash/zsh autocomplete files and minor fixes

contrib/bash_autocomplete

@@ -0,0 +1,23 @@
+#! /bin/bash
+# bash programmable completion for gctcli
+# copy to /etc/bash_completion.d/gctcli and source it or restart your shell
+
+: ${PROG:=$(basename ${BASH_SOURCE})}
+
+_gctcli() {
+  if [[ "${COMP_WORDS[0]}" != "source" ]]; then
+    local cur opts base
+    COMPREPLY=()
+    cur="${COMP_WORDS[COMP_CWORD]}"
+    if [[ "$cur" == "-"* ]]; then
+      opts=$( ${COMP_WORDS[@]:0:$COMP_CWORD} ${cur} --generate-bash-completion )
+    else
+      opts=$( ${COMP_WORDS[@]:0:$COMP_CWORD} --generate-bash-completion )
+    fi
+    COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
+    return 0
+  fi
+}
+
+complete -o bashdefault -o default -o nospace -F _gctcli $PROG
+unset PROG