rails.vim 5.0

* "Projections" greatly enhance the configurability of rails.vim.  See
  the help.
* Drop R from navigation commands (:Emodel, :Smodel, etc).  Old commands
  are still supported.
* Navigation commands provide boilerplate on file creation.
* Run tests with :Rrunner.
* Load :Rails new/:Rgenerate/:Rdestroy results into quickfix.
* Assorted Rails 4 updates.
* :Rails replaces deprecated :Rscript.
* Extract concerns and helpers with :Rextract.
* Switch :Elib default to Gemfile
* Switch :Emigration 0 to db/seeds.rb
* Add :Eschema navigation command.
* Remove support for plugins, including navigation command.
* Detect and support engines with bundler.vim.
* Better :Rpreview support for finding the currently running server.
* Indent settings are no longer automatically adjusted.  Try sleuth.vim.
* Remove configuration provisions superseded by projections.
* Remove assorted seldom used features.