Use #method syntax in controller spec, to match doc

Use 'GET #index' instead of 'GET index', etc. in the scaffold controller
spec, to match the [sample controller specs in the README][1]

[1]: https://github.com/rspec/rspec-rails#controller-specs
Use #method syntax in standalone controller spec

Use `#method` syntax in the generator for the standalone controller
spec, to match the documentation.

/cc @cupakromer
Add line in changelog for #1206 [ci skip]
Merge pull request #1206 from glittershark/controller-spec-method-syntax

Use #method syntax in controller spec, to match doc