Grease lightning

Documentation

• Improvements to the getting started documentation (@am11, #134)

Features

• Add plugin-path CLI option (@mgreter, #149)
• Add Visual Studio 2015 support (@am11, #132)
• Updated to the new LibSass source code layout (@mgreter, #123 #124 #142)

Build

• Improve Makefile compatibility (@mgreter, #120 #121 #122 #150)
• Clean up Makefile (@mgreter, #145)
• Update to the new TravisCI infrastructure (@mgreter, #140)
• Add icon to built sassc executable (@mgreter, #120)

Fixes

• Fix -p flag not working (@saper, #147)
• Fix compilation warning (@driekus77, #128)