4 OE/ORA UI fixes to make it easier to use

- require confirmation when clicking Open Ended reset button
- require confirmation when submitting Open Ended essay
- disable text feedback area during calibration and let users know that they should give feedback when grading
- fixed error message typos

common/lib/xmodule/xmodule/js/src/combinedopenended/display.coffee

@@ -155,7 +155,9 @@ class @CombinedOpenEnded
     @is_ctrl = false
     #Setup reset
     @reset_button = @$(@reset_button_sel)
-    @reset_button.click @reset
+    @reset_button.click ->
+      if confirm "Are you sure you want to remove your previous response to this question?"
+        @reset
     #Setup next problem
     @next_problem_button = @$(@next_step_sel)
     @next_problem_button.click @next_problem
@@ -291,7 +293,9 @@ class @CombinedOpenEnded
     else if @child_state == 'initial'
       @answer_area.attr("disabled", false)
       @submit_button.prop('value', 'Submit')
-      @submit_button.click @save_answer
+      @submit_button.click ->
+        if confirm "Please confirm that you wish to submit your work. You will not be able to make any changes after submitting."
+          @save_answer
       @setup_file_upload()
     else if @child_state == 'assessing'
       @answer_area.attr("disabled", true)
@@ -304,7 +308,7 @@ class @CombinedOpenEnded
         @submit_button.hide()
         @queueing()
         @grader_status = @$(@grader_status_sel)
-        @grader_status.html("<span class='grading'>Your response has been submitted.  Please check back later for your grade.</span> ")
+        @grader_status.html("<span class='grading'>Your response has been submitted.  Please check back later for your grade.</span>")
       else if @child_type == "selfassessment"
         @setup_score_selection()
     else if @child_state == 'post_assessment'

common/lib/xmodule/xmodule/js/src/peergrading/peer_grading_problem.coffee

@@ -27,7 +27,7 @@ class @PeerGradingProblemBackend
     else
       # if this post request fails, the error callback will catch it
       $.post(@ajax_url + cmd, data, callback)
-        .error => callback({success: false, error: "Error occured while performing this operation"})
+        .error => callback({success: false, error: "Error occurred while performing this operation"})
 
   mock: (cmd, data) ->
     if cmd == 'is_student_calibrated'
@@ -460,8 +460,8 @@ class @PeerGradingProblem
       @flag_student_container.hide()
       @answer_unknown_container.hide()
 
-      @feedback_area.val("")
-
+      @feedback_area.val("Once you are done with training and are grading real student essays, you will be asked to share feedback with them in addition to grading their rubric.")
+      @feedback_area.attr('disabled', true)
       @submit_button.show()
       @submit_button.unbind('click')
       @submit_button.click @submit_calibration_essay
@@ -499,6 +499,7 @@ class @PeerGradingProblem
         @change_tracker.rebindTracker()
       else
         @feedback_area.val("")
+      @feedback_area.attr('disabled', false)
       @answer_unknown_checkbox.removeAttr("checked")
       @flag_student_checkbox.removeAttr("checked")
       @submit_button.show()
@@ -509,7 +510,7 @@ class @PeerGradingProblem
     else if response.error
       @render_error(response.error)
     else
-      @render_error("An error occured when retrieving the next submission.")
+      @render_error("An error occurred when retrieving the next submission.")
 
   make_paragraphs: (text) ->
     paragraph_split = text.split(/\n\s*\n/)