[RAILS] Added the "therubyracer" gem into the Gemile in the "basic" template

On Linux, the application fails with "no js library" otherwise.

Closes #44
Closes #38
[RAILS] Added the loading Rails logger integration in the "pretty" template
[RAILS] Added disabling the asset logging integration into the "pretty" template
[RAILS] Updated the automatic Elasticsearch installation to 1.0.1
[RAILS] Replace the Elasticsearch client with plain Net::HTTP
[RAILS] Allowed skipping the automatic Elasticsearch installation

Set RAILS_NO_ES_INSTALL=y environment variable to skip the Elasticsearch installation in the "pretty" template
[RAILS] Re-factored and re-designed the "expert" template

* The Elasticsearch integration is refactored into the `Searchable` concern
* A complex mapping for the index is defined
* A custom serialization is defined in `Article#as_indexed_json`
* The `search` method is amended with facets and suggestions
* A [Sidekiq](http://sidekiq.org) worker for handling index updates in background is added
* A custom `SearchController` with associated view is added
* A Rails initializer is added to customize the Elasticsearch client configuration
* Seed script and example data from New York Times is added (clears Sidekiq queue as well)
* File with Rake tasks for Elasticsearch is added, `rake elasticsearch:import:model` is used to import the data
[RAILS] Allowed to skip `rails server` with the RAILS_NO_SERVER_START environment variable
[RAILS] Added displaying error count in the import Rake task

Prior to this pull-request, these errors would be silently ignored and users might assume that the task had completed successfully. Now the number of errors is printed:

    $ bundle exec rake environment elasticsearch:import:model CLASS=User
    [IMPORT] 4 errors occurred
    [IMPORT] Done

It would be nice to have more details about the errors, but this is an improvement over failing silently.

Closes #48
[MODEL] Small typo fix in the README

Thanks to @bobrenjc93 for the catch!

Closes #26