[BUG] consistency check should not use dir semantics

[doomguy-stg]

Bug Report

Description

The consistency check uses dir semantics, which leads to at least two issues:

• trailing slashes in object name can mask inconsistencies and result in false-positive check results
• Slashes in object names result in unnecessarily long check runtime and a wast of resources.

Steps to Reproduce

I have created tests which illustrate the mentioned issues.

482afb3

[aiivashchenko]

Some implementations are listing objects using dir semantics. Therefore we need to comply.
Of course we'd benefit if it'd be possible to list bucket in a flat manner. We'll look into that.

Other thing is, when empty "directory" is enforced through some client, like web console, it appears as an empty object with trailing slash.
Sometimes it'd have application/x-directory content type, but it is not strictly checked.
As long as object is matching those conditions, it can be used later on as a "directory", i.e. other objects with the same path prefix.
The same reasons are leading to the fact that it is hard to tell whether it is an empty object, or empty "directory".

[aiivashchenko]

Addressed in #174.
Diff is no longer using delimiters in listings.