Use instance variables and render the /search_results view

- Not global variables and redirect to the search_results view. I was
  noticing a conflict in two browsers - a request in one browser for
  YRK and another for GLD, both were showing GLD.
- Don't need a route for /search_results, as a user GETting it
  without passing it any data would error, and now we're using
  render, the user never sees the /search_results route in their
  browser URL bar.
- Splitting the station_name parameter on the ( to get only the first
  portion, the station name, not the abbreviation, left a trailing
  space. The SQL handled this, but it was annoying to see, so strip
  the trailing spaces.