Fix misc issues

While following the instructions to get the app running, I ran into a few miscellaneous issues.

- Running in `development` caused RestClient requests to be sent using WebMock
- Running in `prod` caused an error because `GNIP_USERNAME` was used before it was defined
- The UI didn't display activities if the "Basic Klout" enrichment was enabled but "Premium Klout" was not
- `rake spec` failed because environment variables weren't set

I couldn't get `rake spec:javascript` to pass before or after my changes were made. The error I get looks like:

    Running `phantomjs "/Users/kputnam/.rvm/gems/ruby-2.0.0-p195@search-demo/gems/jasmine-rails-0.4.6/lib/jasmine_rails/../assets/javascripts/jasmine-runner.js" "file:///Users/kputnam/search-api-rails-demo/spec/tmp/runner.html?spec="`
    Running: file:///Users/kputnam/search-api-rails-demo/spec/tmp/runner.html?spec=
    ERROR: Highcharts error #16: www.highcharts.com/errors/16

Since I couldn't get this to pass on a clean branch, I didn't bother to troubleshoot.