enable parallel check of languages

Use parallel to spawn as many subprocesses as possible to accelerate
the tests.
Change Maruku check to fully functional mode

this is cleans up the code.
Force output of Rake messages to stderr
Update command line output in Chapter 4.2

The command line output in the examples is from an older version of Git
(1.7.*) and is slightly inconsistent with the latest version.
Update command line output in Chapter 4.5

The command line output in the examples is from an older version of Git
(1.7.*) and is slightly inconsistent with the latest version.
Update command line output in Chapter 4.7

The command line output in the examples is from an older version of Git
(1.7.*) and Gitosis. Both being slightly inconsistent with the latest
versions.
Reviewed "About Version Control"
Reviewed "Local Version Control Systems"
Reviewed "Centralized Version Control Systems"
Reviewing "Git Basics"

Reviewed:
Git Basics
Snapshots, Not Differences
Reviewing "Git basics"
Merge pull request #664 from daftano/master

[it] update chapter 1
Merge pull request #651 from Matt-Stevens/update-commandline-output-ch4

Update commandline output in Chapter 4
Merge pull request #666 from YueLinHo/master

[zh-tw] Synchronize with En version
Reviewing "Git Basics"
[it] reviewed "Git Basics"
[it] Reviewed "Installing Git"
Reviewed "First-Time Git Setup"
[it] fully reviewed chapter 1
Use GitHub endpoint for Gitosis

Fixes:

    git clone git://eagain.net/gitosis.git
    Cloning into 'gitosis'...
    fatal: unable to connect to eagain.net:
    eagain.net[0: 192.237.217.227]: errno=Connection refused
    eagain.net[1: 2001:4800:7813:516:fa64:3a5d:ff04:7851]: errno=Network is
      unreachable