Code is now idempotent

- alias section is now conditionally added (adds only if it doesn't exist)
- each command in alias is now conditionally added under alias (makes it easier for updating)
- paths are conditionally updated
- paths should also work in windows...please test this out b/c I don't have access to a windows right now (if you can test it on a clean machine that'd be great)
- git-top command now called for all aliases (so students don't have to cd to the toplevel project dir)