Allow justel library to return only text

[geektortoise]

Currently, with the soup2md method, we have

• a text {text_meta}{text} if the meta_out argument is not set
• a two value return if the meta_out argument is set

It could be useful to return only the core text

[geektortoise]

My problem was that the meta data was included in a markdown formatted text. I add a function in the justel_lib that allow to extract unformatted text and metadata. https://github.com/openjusticebe/be_law_tools/commit/75a0272c8c6e25eed0f52445c77857ecd636c20b

Metadata can be ignored by the caller if not needed.

This ticket can be close if the commit will be merged into the master branch See https://github.com/openjusticebe/be_law_tools/issues/22