Update .travis.yml link to official vim repo

Author: ryanss

.travis.yml

@@ -12,9 +12,7 @@ install:
 before_script:
     - flake8 ftplugin/hackernews.py
     - if [ $PYVERSION = 3 ]; then
-        sudo apt-get update;
-        sudo apt-get install python3-dev;
-        hg clone https://code.google.com/p/vim/;
+        git clone https://github.com/vim/vim.git;
         cd vim;
         ./configure --enable-python3interp;
         make;