trigger datepicker when planting finished checkbox is ticked

Gemfile

@@ -83,6 +83,10 @@ group :development do
   # Installation of the debugger gem fails on Travis CI,
   # so we don't use it in the test environment
   gem 'debugger'
+  # A debugger and irb alternative. Pry doesn't play nice
+  # with unicorn, so start a Webrick server when debugging
+  # with Pry
+  gem 'pry'
   gem 'better_errors'
   gem 'binding_of_caller'
   gem 'letter_opener'
@@ -119,7 +123,6 @@ gem 'omniauth-flickr', '>= 0.0.15'
 gem 'rake', '>= 10.0.0'
 
 group :development, :test do
-  gem 'pry'
   gem 'haml-rails'                   # HTML templating language
   gem 'rspec-rails', '~> 2.12.1'     # unit testing framework
   gem 'database_cleaner', '~> 1.3.0'

app/assets/javascripts/finish_planting.js.coffee

@@ -1,7 +1,7 @@
 # Clears the finished at date field when
 # a planting is marked unfinished, and
 # repopulates the field with a cached value
-# marking unfinshed is undone.
+# marking unfinished is undone.
 
 jQuery ->
   previousValue = ''
@@ -10,7 +10,9 @@ jQuery ->
     if @checked
       if previousValue.length
         date = previousValue 
-      finished.val(date)
+        finished.val(date)
+      else
+        finished.trigger('focus')
     else
       previousValue = finished.val()
       finished.val('')