[ko] translation update

[ko] translation update ch1 to ch4

[ko] translation update ch5

[ko] translation update ch6

[ko] translation update ch7

[ko] translation update ch8

[ko] translation update ch9

[ko] proofreading.

[ko] fix mistyping.
[ko] update translation.

Conflicts:
	ko/03-git-branching/01-chapter3.markdown
	ko/04-git-server/01-chapter4.markdown
	ko/07-customizing-git/01-chapter7.markdown
Merge pull request #526 from dogfeet/ko

[ko] update translation.