Split out project-specific configuration

[grodtron]

Set up something where I can give a github project as an input, and it will be cloned and set up as part of bootstrapping.

It would also be cool to then set up a corresponding convention for specifying additional set up steps in the package. Examples include:

• Installing additional tools (e.g. install kotlin, clj, clang at a specific version, etc.)
• "Injecting" entries into the shell history for common useful commands
• Setting up shell aliases specific to the project

[grodtron]

This also would have the benefit of slimming down the overall bootstrap, as now it installs everything I might ever possibly need