Update betty version due a a security fix

Signed-off-by: Clement Escoffier <clement.escoffier@gmail.com>
Change name of the read me file to README.asciidoc

Signed-off-by: Clement Escoffier <clement.escoffier@gmail.com>
Fix #195

Also fix inconsistent property names.

Signed-off-by: Clement Escoffier <clement.escoffier@gmail.com>