avoids docInfo files from being copied in refresh mojo

[abelsromero]

Thank you for opening a pull request and contributing to asciidoctor-maven-plugin!

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Documentation
• Refactor
• Build improvement
• Other (please describe)

What is the goal of this pull request?
Replicates the logic from process-asciidoc mojo that prevents docInfo files from being copied into the output directory.

Are there any alternative ways to implement this?
Following previous pattern, files that are not required in output ar filtered by ResourceCopyFileAlterationListenerAdaptor using a filename regular expression.
To make the pattern easier to mantain the logic has been extracted into a class ResourcesPatternBuilder with proper unit tests for it.

Are there any implications of this pull request? Anything a user must know?
Also includes:

• Moved all constants related with extentions, and file patterns to AsciidoctorFileScanner
• Minnor refactoring of AsciidoctorFileScanner. Mostly formatting.

Is it related to an existing issue?

• Yes
• No
  Indirectly related with Support auto-refresh with minimal features to be usefull #472.
  I don't identify any missing feature now.

Finally, please add a corresponding entry to CHANGELOG.adoc

[coveralls]

Coverage increased (+0.1%) to 82.702% when pulling eeb2cd2 on abelsromero:feature/do-not-copy-special-resources-in-refresh-mojo into 460e1b9 on asciidoctor:master.