Add minimal bash support with completion

Bash users should add to their .bashrc:
source path/to/dir/cd-bookmark/cd-bookmark

Reference for completion implementation:
https://opensource.com/article/18/3/creating-bash-completion-script

Fixes #6

README.md

@@ -1,7 +1,7 @@
 # cd-bookmark
 
 ## Synopsis
-zsh plugin to bookmark directories to cd.
+zsh and bash plugin to bookmark directories to cd.
 
 Inspired by [mokemokechicken post](http://qiita.com/mokemokechicken/items/69af0db3e2cd27c1c467) and shell script in the post.
 
@@ -47,6 +47,12 @@ e.g.
 alias cdb='cd-bookmark'
 ```
 
+#### Bash
+For bash users, put this in your shell initialization file (typically `$HOME/.bashrc`):
+```
+source path/to/dir/cd-bookmark/cd-bookmark
+```
+
 ## Usage
 
 

cd-bookmark

@@ -226,10 +226,29 @@ function _cdbookmark_main() {
   esac
 }
 
+function _cdbookmarks_bash_completions() {
+  if [ "${#COMP_WORDS[@]}" = "2" ]; then
+    local word_list=(-a -c -d -l -e -p -h)
+    COMPREPLY=($(compgen -W "${word_list[*]}" -- "${COMP_WORDS[1]}"))
+  elif [ "${#COMP_WORDS[@]}" = "3" ] && [[ "${COMP_WORDS[1]}" =~ ^-[acdp]$ ]]; then
+    local word_list="$(_cdbookmark_list_bookmark_id)"
+    COMPREPLY=($(compgen -W "${word_list[*]}" -- "${COMP_WORDS[2]}"))
+  fi
+}
+
 #set -o xtrace
 #set -o verbose
 
-_cdbookmark_main "$@"
+if [ -n "$ZSH_VERSION" ]; then
+  # zsh entry point (executed as function from $(autoload -Uz))
+  _cdbookmark_main "$@"
+else
+  # bash entry point (executed as a sourced function)
+  function cd-bookmark() {
+    _cdbookmark_main "$@"
+  }
+  complete -F _cdbookmarks_bash_completions cd-bookmark
+fi
 
 #set +o xtrace
 #set +o verbose