dblatex hates files with multiple periods

dblatex hates files with multiple periods

Running the PDF transform was generating errors from dblatex complaining
about unknown file extensions like ".50_Import1.jpg"; this was because
there were two periods in the file name. Easily fixed by renaming the
files, and I removed the useless ALT text from the image attributes in
the same pass.

Signed-off-by: Dan Scott <dan@coffeecode.net>