Add numeric color values to 07-customizing-git.

en/07-customizing-git/01-chapter7.markdown
	-Explain that, when colorizing `git` output, users can specify arbitrary
	numeric color values instead of color names.
Smooth out intro from using too many begins
Merge pull request #803 from randomecho/en-chap-1-intro

Smooth out intro from using too many begins
Merge pull request #802 from sevko/master

Add numeric color values to 07-customizing-git.
Merge branch 'progit/master'