Title should be always a string

Even when the author put in a number

* Fix `middleman article --blog [name]` command... 

Get the blog instance matching the provided --blog instance by finding on the blog name, instead of the hash key.

* Update article.rb

* Support opening an editor after creating a post

* Get rid of an extraneous line

* Extract the File.join into a variable

This fixes the call to the external editor to, as I copied the line from
my old revision of this change. The API has since changed in the
intervening 2 years, so update my code to match.

* Fix article subdirectory files when used with directory_indexes and permalink without extension

* Fix app name in cucumber feature

* Also fix subdirectory files for permalinks containing dots (other than an extension)

Fix summary generation

resolves #296 recognize :_auto_layout value for layout

This fixes #279. Now summary is always shown up to the separator even when a length is specified, and separators that are HTML comments also work. Tests have been modified to reflect this desired behavior.

- recognize :_auto_layout value as equivalent of nil
- add missing test dependency

Pull in article command from v3.5.3 tag

Add filter option