[Redmine] Add status mapping

Status values were stored as integer identifiers in "changes" table.
This commit fixes this problem storing their text values instead of
those ids.
[Database] Set TEXT datatype in fields of "changes" table

The previous datatype for these fields was VARCHAR(255) that
can crop long menssages. This casued problems in incremental mode
because when the new values to insert were compared to those already
inserted, the result was false, inserting twice the same data.