cmake is required during the installation of the rugged gem

The following error is encountered during the installation of the rugged gem:

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    /usr/bin/ruby2.1 extconf.rb
    checking for cmake... no
    ERROR: CMake is required to build Rugged.
    *** extconf.rb failed ***
Document characters being stripped from labels
Update changelog.
label documentation
add required permission to label doc
Merge branch 'label-doc' into 'master'

Label doc

Fixes #1487

See merge request !1028
Call updateColorPreview in Labels constructor
Fix spelling error in merge request performance issue warning.
Fix tests after #7526
update ruby & gitlab shell config

ruby 2.0.x required for gitlab 7.0+
Merge branch 'fix_labels_edit' into 'master'

Fix labels preview color when edit

This is related to #515. Parentheses are missing in coffeescript. For this reason, the color preview is not updated when loading the labels edit page.

See merge request !173
Merge pull request #7557 from Razer6/fix_tests

Fix merge request API after #7526
Merge branch 'master' of gitlab.com:gitlab-org/gitlab-ce
Merge branch 'master' of github.com:gitlabhq/gitlabhq
Make sure the test fails in year 2114.
Merge pull request #7555 from erikjwaxx/master

Fix spelling error in merge request performance issue warning.
Add dependency info for mysql-postgresql converter

Running converter with Python 2.6.x installed gives the following error:
AttributeError: 'module' object has no attribute 'check_output'

After installing Python 2.7.x everything works fine.
Merge pull request #7540 from sameersbn/docs-install-cmake

cmake is required during the installation of the rugged gem
Merge branch 'update_changelog' into 'master'

Update changelog

Fixes #1509

See merge request !1026
Merge branch 'explain_migration' into 'master'

Explain label migration

See merge request !1025