Generalize quickfix list shortcuts
Restore `gd` functionality

- Makes `gd` only run `:Gdiff` again
- Adds `g3d` shortcut for the 3-way diff
Add initial tests for bin

- Creates basic test infrastructure
- Add tests for `get-paths` and `get-aliases`
Add `.travis.yml`
Fix tests
Update readme
Merge pull request #16 from alexdavid/qfl_shortcuts

Generalize quickfix list shortcuts
Merge pull request #20 from alexdavid/tests

Add initial tests for bin
Merge pull request #17 from alexdavid/gd_functionality

Restore `gd` functionality