Merge pull request #91 from s0undt3ch/merge-stable/1.5.1

Merge current develop(1.5.1) branch into stable(1.5) making stable 1.5.1
Merge pull request #98 from saltstack/develop

Let's make 1.5.2 stable.
Merge pull request #106 from saltstack/develop

Bump Stable Version to 1.5.3
Merge pull request #116 from saltstack/develop

Update Stable
Merge pull request #155 from s0undt3ch/develop

Merge current develop branch into Stable
Merge pull request #157 from saltstack/develop

Update Readme
Merge pull request #159 from saltstack/develop

Bump Stable Version to 1.5.5
Merge pull request #195 from saltstack/develop

Merge current develop branch into Stable for 1.5.6
Merge branch 'develop' into stable, making 1.5.7 the current stable release.
Merge pull request #241 from s0undt3ch/stable

Make 1.5.7 the next stable release
1.5.8 is the current develop version
add-apt-repository was moved to software-properties-common in version 12.10.
Fix bashism.
Update changes log and add Diego Woitasen(@diegows) to authors.