add fish shell support
move homeshick.fish to project root
Fix fish shell install command
Much better intro, such drama, much lofty, wow
Fixes #82. Switch to bats.
Test cases are now a lot simpler and the setup more modularized.
The interactive script and the test suites now share a common helper file.
Fixes #31: Make track work with directories
WIP! Still needs a lot of unittests
Add .travis.yml to run CI