Fix #4; Adjust default parallel job based on CPU count

[ohpauleez]

This pull-request makes the following updates:

• Fix issue call isatty on stdout before colouring output #4 by setting nocolor's default value based on the stdout atty value. This introduces a new dependency on go-isatty.
• Set the default parallel number to Go's runtime NumCPU
• Add a general .gitignore for the project.
• Fix a typo in the README; Set headers semantically (they're all about the same topic, Mk)