added basic cli parser

src/kotatsu.cr

@@ -1,6 +1,21 @@
 # TODO: Write documentation for `Kotatsu`
+
+require "option_parser"
+
 module Kotatsu
   VERSION = "0.1.0"
 
-  # TODO: Put your code here
+  OptionParser.parse do |parser|
+    parser.banner = "Kotatsu - Easy to configure server start page"
+
+    parser.on "-h", "--help", "Show this help" do
+      puts parser
+      exit
+    end
+
+    parser.on "-v", "--version", "Show kotatsu version" do
+      puts VERSION
+      exit
+    end
+  end
 end