add install option for zsh completion function

README.mdown

@@ -36,6 +36,15 @@ If you're on a Mac and use [homebrew](http://github.com/mxcl/homebrew), it's sim
 
     $ brew install https://github.com/iwata/git-now/raw/master/git-now.rb
 
+#### install options
+ * use ``gnu-getopt``
+
+        $ brew install --gnu-getopt https://github.com/iwata/git-now/raw/master/git-now.rb
+
+ * copy zsh completion function to ``fpath``
+
+        $ brew install --zsh-completion https://github.com/iwata/git-now/raw/master/git-now.rb
+
 ### Manual installation
 If you prefer a manual installation, please use the following instructions:
 

git-now.rb

@@ -1,8 +1,8 @@
 require 'formula'
 
 class GitNow < Formula
-  url  'https://github.com/iwata/git-now.git', :tag => 'v0.1.0.3'
-  version '0.1.0.3'
+  url  'https://github.com/iwata/git-now.git', :tag => 'v0.1.0.4'
+  version '0.1.0.4'
   head 'https://github.com/iwata/git-now.git', :branch => 'develop'
   homepage 'https://github.com/iwata/git-now'
 
@@ -11,15 +11,19 @@ class GitNow < Formula
   end
 
   # for longopt
-  if ARGV.include? '--ln-gnu-getopt'
+  if ARGV.include? '--gnu-getopt'
     depends_on 'gnu-getopt'
   end
 
   def install
     system "make", "prefix=#{prefix}", "install"
-    if ARGV.include? '--ln-gnu-getopt'
+    if ARGV.include? '--gnu-getopt'
       system "brew ln gnu-getopt"
     end
+    if ARGV.include? '--zsh-completion'
+        fpath = `echo $fpath |cut -d ' ' -f 1`
+        system "cp etc/_git-now #{fpath}"
+    end
   end
 
 end