Add travis badge to README.md
Add travis badge to README.md

Also update build instructions for autogen.sh change.

Signed-off-by: Ralph Giles <65585f72bf62a11d2f4105aa30c20fe94efea46f@mozilla.com>

eidy/libogg,ksophocleous/ogg,brion/ogg,youfearm3/ogg,brion/ogg,nicolaichuk/ogg,xiph/ogg,xiph/ogg,ksophocleous/ogg,ShiftMediaProject/ogg,youfearm3/ogg,felipebetancur/ogg,emscripten-ports/Ogg,eidy/libogg,felipebetancur/ogg,mwgoldsmith/ogg,emscripten-ports/Ogg,ShiftMediaProject/ogg,nicolaichuk/ogg,mwgoldsmith/ogg