add $.fn.indicateLoading for when you don't need to disable

we have $.fn.disableWhileLoading  that is great for
when you want to disable an element while a deferred
(ajax request) is working.  this is for when you just
want to show a little loading icon, and is a lot lighter
weight.

Change-Id: I0271c9be9a5bb84e1faae5d94f09bac8a718c70e
Reviewed-on: https://gerrit.instructure.com/16035
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Clare Hetherington <clare@instructure.com>
Reviewed-by: Sterling Cobb <sterling@instructure.com>

app/coffeescripts/jquery/indicateLoading.coffee

@@ -0,0 +1,14 @@
+define [
+  'jquery'
+], ($) ->
+  
+  # possible values for position are 'center' and 'after', see g_util_misc.sass
+  # passign a position is optional and if ommited will use 'center'
+  $.fn.indicateLoading = (position, deferred) ->
+    unless deferred?
+      deferred = position
+      position = 'center'
+    @each ->
+      $this = $(this).addClass 'loading ' + position
+      $.when(deferred).done ->
+        $this.removeClass 'loading ' + position

app/stylesheets/g_util_misc.sass

@@ -231,3 +231,16 @@ a.x-close-link
     color: black
     text-decoration: none
     +opacity(.60)
+
+.loading.after:after
+  width: image-width('ajax-loader-linear.gif')
+  height: image-height('ajax-loader-linear.gif')
+  background: url(/images/ajax-loader-linear.gif)
+  content: ''
+  display: inline-block
+  margin-left: 7px
+
+.loading.center
+  background-image: url(/images/ajax-loader-linear.gif)
+  background-position: center
+  background-repeat: no-repeat