allow to match against filename in --to-regexp-map, and a fix for pod-spelling

Hi, 
while working on https://bugs.mageia.org/show_bug.cgi?id=1095 , I found out that SVN::Notify would only match against directory name, and not against filename. So here is a patch to enable this behavior. 

To test, I created a small svn in /tmp/svn/foo, with a file coin/foo.pot, and triggered svnnotify with that :

PERL5LIB=$(pwd)/lib  bin/svnnotify --repos-path /tmp/svn/foo/ --revision  2  --to-regex-map "misc@example.org=\.pot$"

Without the patch, it does nothing, with the patch, it send a email. I ran the tests, nothing fail, and tested if the regular functionnality was still ok, and it worked. I also quickly fixed the pod and comments.

There is also a fix for pod-spelling, that is saying that GitHub is a spelling error.