fixes install target, adds travis badge, invokes make test

edit README.md
 * adds travis status badge

edit Makefile
 * fixes install target to depend on youtube-dl.fish
 * fixes README.md target to invoke youtube_dl compliant with python-2.6

edit .travis.yml
 * adds pre-install verbosity
 * pandoc installation
 * make, make test, sudo make install,
This changes the script target by a lot. I'm not sure who uses it, but you may want to define a new target.