added .gitignore file

... and populate it with autotools/build files.
This is of course intended to make life easier for people using git-svn.

Signed-off-by: intrigeri <intrigeri@boum.org>

.gitignore

+Makefile.in
+aclocal.m4
+autom4te.cache/
+configure
+etc/Makefile.in
+examples/Makefile.in
+handlers/Makefile.in
+install-sh
+lib/Makefile.in
+man/Makefile.in
+missing
+src/Makefile.in
+Makefile
+backupninja.spec
+config.log
+config.status
+etc/Makefile
+etc/backupninja.conf
+etc/cron.d/backupninja
+etc/logrotate.d/backupninja
+examples/Makefile
+handlers/Makefile
+handlers/dup
+handlers/dup.helper
+handlers/ldap
+handlers/ldap.helper
+handlers/maildir
+handlers/makecd
+handlers/makecd.helper
+handlers/mysql
+handlers/mysql.helper
+handlers/pgsql
+handlers/pgsql.helper
+handlers/rdiff
+handlers/rdiff.helper
+handlers/rsync
+handlers/sh
+handlers/svn
+handlers/sys
+handlers/sys.helper
+handlers/trac
+lib/Makefile
+lib/easydialog
+lib/parseini
+lib/tools
+lib/vserver
+man/Makefile
+src/Makefile
+src/backupninja
+src/ninjahelper