Adds search by city functionality to app

* Link to search page as home page from link in header (landings#index)
* Route index action in landings_controller to render :show
* Adds search in searches_controller with methods in user model
* Adds search show page with user partial to display dr results
* Disables high-voltage root path
Removes high_voltage initializer and Guest user that isn't used
Merge pull request #8 from Psychologist-Today/dr_search_feature

Adds search by city functionality to app