Bug 13897: Process description, multiline values and SQL statements in YAML files

Bug 13897: Process description, multiline values and SQL statements in YAML files

This patch adds 3 features:
1) Display description of YAML files at install time
   for frameworks, and fixes it's encoding.
2) Enable use of multiline values, field required
3) Process SQL statements declared in YAML files

With this features we can process files with the
following generic YAML strucure:

  ---
  description:
    - "File description"

  tables:
    - table_name:
        translatable: [ title, content ]
        multiline: [ content ]
        rows:
          - title: "Example title"
            content:
              - "Content:"
              - ""
              - "This is the content."
            id: 1
            value: ~

  sql_statements:
    - "UPDATE table_name SET value ='empty' WHERE value IS NULL"
  ...

* file description is now inside the YAML, can have multiple
  lines.
  This attribute is expected in all YAML files.
* translatable attribute in table declare fields that can be
  translated
* multiline attribute in table declare fields that can have
  multiple lines of content, they are joined using '\r\n'
  before insert into database.
  This is useful to express fields like 'news' content, and
  to simplify it's translation.
  '\r\n' is used for correct display in Windows clients.
* sql_statements allows to add multiple SQL sentences, not
  insertions normally, that are executed in order.

This features are not needed for the example file of this patch,
but will be used in new bugs.

To test:
1) Use the same test plan of first patch.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>