Claim maintainership for block2mtd and update email addresses

I have been prime author and maintainer of block2mtd from day one, but
neither MAINTAINERS nor the module source makes this fact clear.  And while
I'm at it, update my email addresses tree-wide, as the old address
currently bounces and change my name to "joern" as unicode will likely
continue to cause trouble until the end of this century.

Signed-off-by: Joern Engel <joern@lazybastard.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>