One line installation (via CLI)

A simple way to install lunchbox.

Relying on the user to copy and paste is prone to error. This method requires the user to execute a one-line command which creates a copy of lunchbox in /Users/user/local/bin/. One file, no modifications, no fuss.

Note: Installation path inside lunchbox-installer and README.md will need to be updated if merged in to bigspring/lunchbox