add bash completion

tools/cryptr-bash-completion.bash

@@ -0,0 +1,14 @@
+_cryptr_complete()
+{
+     local cur_word prev_word type_list
+     COMPREPLY=()
+     cur_word="${COMP_WORDS[COMP_CWORD]}"
+     prev_word="${COMP_WORDS[COMP_CWORD-1]}"
+ 
+     opts='encrypt decrypt'
+ 
+     COMPREPLY=( $(compgen -W "${opts}" -- ${cur_word}) )
+     return 0
+}
+ 
+complete -F _cryptr_complete cryptr.bash cryptr