Started work on welcome view

The biggest change here is that CSS styles are no longer defined in
index.html. Instead, they are defined on a per-state basis in app.js.
This was due to the fact that there were a large number of (necessary)
conflicting styles between main.css and welcome.css.
Added skeleton welcome screen.
Created endpoints for customer and vendor sign up.

Currently, signing up as a new vendor will null out all of the
vendor/address fields.
Added an already exists modal and hooked up register drop down.
Added cookie for welcome screen.
Updated content for welcome page.
Added a background image for fun.
Renamed /seller page to /vendor

This makes us more consistent with the /vendor/details page.
Added Facebook icons to sign in

This is per the mentor’s request as they wanted more clarification that
Facebook would be used to sign in. I didn’t put an icon on the sign in
button as I figured people would remember once they created an account
that Facebook was used.
Updated views to only show active vendors.

Forgot about this part of the workflow refactor. Also updated
permission classes on several endpoints, as they were insecure.
Setting vendor.compay_name to name on first creation

By doing this, we can simply display vendor.company_name always in the
profile view.
Added My Account button for customers and vendors

Currently, this does nothing for customers. It should probably also be
a dropdown in the future once we have more user options.
Fixed vendor cards to only display in stock items
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.
Fixed permissions error with editing locations.
Merge branch 'master' into workflow-refactor

Conflicts:
	src/client/app/index.html
	src/client/app/scripts/app.js
	src/client/app/scripts/directives/navbar.js
	src/server/be_local_server/models.py
	src/server/be_local_server/views.py
fixed spelling mistakes & changed fonts on splash page
Merge branch 'workflow-refactor' of https://github.com/rpanjwani/beLocal into workflow-refactor
Fixed is_active and workflow bugs.

Vendors now have an is_active flag since Django was blocking us from
doing anything useful when django.contrib.auth.models.User.is_active
was set to false.