Added 'likes' to Product model and created REST endpoints.

- 'likes' uses django-secretballot app
- Add custom middleware for likes. Only authenticated users can like a product.
- REST endpoint to like/unlike a product.
- GET method tells whether the product is currntly liked by the authenticated user.

Setup Instructions:
- Install django-secretballot app :  pip install django-secretballot
Send total likes for each product.

- Added total_votes field to ProductDisplaySerializer.
Return authenticated user vote with product details.

- Add isLiked field to serializers.
- isLiked is 1 if user has liked the product, else null.
- isLiked is return whenever product details is retrieved.
- REST endpoints:
	vendor-products-list
  product-trending-list
  vendor-products-details
Implement basic UI, controller and service for product likes.

- like/unlike button that also shows total likes.
- currently UI implementation is done for productCard only.
- Small tweak in JSON response in server view.
- Small tweak in REST test cases.
Improved UI design for 'like' button.
Merge branch 'master' of github.com:rpanjwani/beLocal into likes

* 'master' of github.com:rpanjwani/beLocal: (38 commits)
  Added error message for logging in without an account.
  Fixed is_active and workflow bugs.
  fixed spelling mistakes & changed fonts on splash page
  Fixed Twitter posting bug to do with escaped characters.
  Delete icon_apple_braeburn_DBSHKIz.png
  Delete icon_apple_braeburn.png
  Delete Screen_Shot_2014-09-30_at_1.34.48_PM.png
  Delete 500px-Supplemental_Nutrition_Assistance_Program_logo.svg.png
  Delete icon_apple_braeburn_1.png
  Delete icon_apple_braeburn.png
  Delete Lettuce_1.jpeg
  Delete Grapes_1.jpeg
  Delete Grapes.jpeg
  Fixed editing of vendor profile pictures
  Carly made me do it.
  Validation added for the vendor's profile editing.  Icon for editing vendor profile changed to a button.
  Fixing mismatched curly braces.
  Added the ability to post to Twitter.
  small UI changes
  fixed the product inventory card
  ...

Conflicts:
	src/client/app/scripts/app.js
	src/server/be_local_server/views.py
	src/server/server/urls.py
changed isLiked to is_liked for consistency.
fixed vendor object to return if vendor is active
Redesigned like button.

We still need to add a tooltip to the disabled button telling the user
to log in if they want to like products.
Added tooltips for disabled buttons prompting sign in

Also ensured that StateService.currentUser is cleared on logout.
Finalized product card UI and fixed registration redirection workflow.
Merge pull request #30 from rpanjwani/likes

Likes