This new setting is used to limit the number of bytes read
while determining the MIME type of a new document. A value
of 0 will cause the entire file to be loaded into memory.
1024 appears to be a suitable number for most cases. This
setting defaults to 0 to preserve the current behavior but
might change in a future version.
Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>