Adds an endpoint for the login to hit

* keeps a dynamic segment to pass in the provider name
* the intention is to store sessions with access tokens
* login params from linkedin take this form

```
{
    "code"=>”temporary-access-code”,
    "state"=>”string used for securing purposes”,
    "controller"=>"sessions",
    "action"=>"create",
    "provider"=>"linkedin"
}
```
config db

This is not great practice, but acceptable because heroku will take
care of all the db permissions
adds a session model with db table
adds dotenv
generate rspec
sets up test env
adds test for sessions#create
make route more resourceful

this route still assigns a get request to a create action, but IMHO
it’s better to cross these in the router than have a show request
that’s doing a lot of creating work
adds session creator to sessions create action

create implementation on its way!
exchanges the temp code for an access_token

*  adds a Linkedin module with a facade method to access the linkedin
API
*  adds a linkedin client, which will likely spawn a gateway class
adds a sessions map and finishes of the creation of the session
gems multi_xml, thin, hashie, pry
removes unnecessary assignment
refactors linkedin client

* now uses mostly methods on the instance
removes faraday logger
gets tests passing
adds fields to the linkedin find query

This is not the prettiest thing I’ve ever done :/
adds a user from sessions create

Still need a user model!
adds a user model

* RUN MIGRATIONS
associates sessions with a user

* RUN MIGRATIONS