Minor update

Efficiency...
Better error management

using `.catchError` is a good practice to cacth errors throws during the `then` handler.
Fix syntax error.
avoid duplicate ids in ng-repeated span (category-filter)

Eliminated the need for the <span> id by putting the span inside the
<label>.
unnecessary test for null removed from CategoryFilter.call

No need to test for (filterMap != null) immediately before the conjunct
(filterMap is Map) since (null is Map) is false.
Merge pull request #45 from pavelgj/master

fix(Chapter 7): fixed parser gen header file
Use NgAttrs instead of map

Review URL: https://codereview.appspot.com/53960043
Merge pull request #39 from chalin/patch-1

avoid duplicate ids in ng-repeated span (category-filter)
Merge pull request #40 from chalin/patch-2-unneeded-test-for-null

unnecessary test for null removed from CategoryFilter.call (Chap. 5-7)
Cleaned up imports (unused and missing) and tweaked test (Ch.2 to 6)

 - Cleaned up imports, unused and missing (Ch.2 to 6).
 - Adjusted called to Recipe constructor in main_test (Ch.5&6).
 - Chose not to touch Chapter 7 code given that there are other pending
changes for it.
Merge pull request #46 from chalin/patch-4-mainly-import-cleanup

Cleaned up imports (unused and missing) and tweaked test (Ch.2 to 6)
Merge pull request #37 from bgourlie/patch-2

Fix syntax error.
Add screenshot for ch02

Review URL: https://codereview.appspot.com/57940043
Add a second screenshot for ch02

Review URL: https://codereview.appspot.com/57970043
Fix image size

Review URL: https://codereview.appspot.com/57980043
Merge pull request #21 from vicb/patch-7

Better error management
Merge pull request #20 from vicb/patch-6

Minor update
avoid duplicate ids in ng-repeated span (Chap. 6-7)

Oups, sorry, missed these before; this time, making the fix in all
remaining chapters (lib/component/search_recipe_component.html).
Drop cssUrl parameter to NgComponent since .css is empty (Chap. 6-7)

The component folder holds the files for the two components
search_recipe and view_recipe. Given that one of these has an empty
.css file, it seems reasonable to drop it, reducing the clutter and
driving home the fact that the `cssUrl` parameter is optional.
Merge pull request #52 from chalin/patch-6-drop-empty-component-css

Drop cssUrl parameter to NgComponent since .css is empty (Chap. 6-7)