REST endpoints for adding tags to a product & display product tags

- add tags to a product (vendor-products-add)
- return product tags with product details : add tags to the product serializers.
Merge branch 'master' into product-tags

* master:
  Removed like buttons on all responsive cards.
  Removed like button from vendor card.
  Fixed user profile editing.
list all available tags.
REST endpoint to get a list of products having a given tag.
add REST endpoints to add/edit/view category of a product.

- create category data model
- add category to product
- modify REST endpoints of products to add/edit category
create REST endpoints to view list of products/categories.

- view a list of categories.
- view a list of products of a given category.
add category to items.
new header design
header is working on large display - need to make it responsive
Changed colours on the header
dropdown button for category.
Merge branch 'master' of github.com:rpanjwani/beLocal into product-tags

* 'master' of github.com:rpanjwani/beLocal: (37 commits)
  Added title
  add partial searching to more vendor fields
  enabled partial matching for vendors and cleaned up indexes
  Removed space for categories (for now)
  Added product details modal to search results.
  Removed debug statements and made empty search results pretty
  Removed query string from url
  Completed basic search UI
  Fixed seller location editing
  Refactored client side to begin search UI
  added examples populating search views
  added product and vendor search views
  Hooked up images to market cards.
  Added images for markets
  UI changes to markets cards
  Finalized market card UI
  Fixed vendor card hit box.
  Changed tab color
  Fixed vendor card serializers.
  Fixed market joining workflow
  ...

Conflicts:
	src/server/be_local_server/views.py
	src/server/server/urls.py
basic UI for add/edit tags and categories and to list categories.
script to add tags and categories.
Header UI for very large & large displays
Changed category dropdown

Added bootstrap styling and also removed default value in favour of
adding an Uncategorized category server-side. (updateTagCategory.py has
been updated to reflect this).
Converted product details modal to directive

Since there are going to be some changes made to this modal for
categories/tags, I figured it would be best to pull this into its own
file.
Header UI for medium displays
Updated UI for categories list and product details modal
add tags list to main page and fix update tags.