refactor the naming within plugin new generator

Having a method called `full?`, which checks on :full and :mountable
is very confusing. I renamed `full?` to `engine?` and created a `full?`
method that only checks the `:full` option
Relation.where with no args can be chained with not, like, and not_like

examples:

  Model.where.not field: nil
  #=> "SELECT * FROM models WHERE field IS NOT NULL

  Model.where.like name: 'Jeremy%'
  #=> "SELECT * FROM models WHERE name LIKE 'Jeremy%'

this feature was originally suggested by Jeremy Kemper https://github.com/rails/rails/pull/5950#issuecomment-5591330

Closes #5950
Use attr_accessor for Rails.{application,cache,logger}
Add periodical-style TOC and navigation to Kindle version of guides
add a notice about loading assets in production mode
Merge pull request #120 from tonytonyjan/patch

add a notice about loading assets in production mode
Correct bad English
Define a generator before referring to it
dump schema.rb without :version option
Merge pull request #8431 from joshsusser/schemadump

dump schema.rb without :version option
Introduce Bundler and Gemfiles in a NOTE
correct bad jquery syntax
adding example for f.file_input
adding example for f.file_input
complementary options guidelines for f.file_field and file_field_tag
API reader should look elsewhere for helper instructions
adds a couple of items to the check list for stable releases [ci skip]
Add comment about implementation of class_attribute

To prevent future pull requests like #8435 add a comment about the
implementation of class_attribute using class_eval for performance.

[ci skip]
Refactor tests that switch RAILS_ENV and RACK_ENV

This cleanup aims to fix a build failure:
https://travis-ci.org/rails/rails/jobs/3515951/#L482

Since travis always have both ENV vars set to "test", a test is failing
where it's expected to output the default env "development", but "test"
is the result due to RACK_ENV being set when we expect it to not be.

By cleaning this duplication we ensure that changing any of these env
variables will pick the right expected value.
convert time to string

why is this a Time to start with?