fix(dependencies): Revert two breaking dependency updates
fix(dependencies): Revert two breaking dependency updates

gulp-sourcemaps was updated to 2.0.0-alpha which is not ready for release, reverted back to 1.5.2.
Chai was updated to 3.5.0 which is outside the dependency range of chai-fs, reverted back. Chai-fs
is in the process of updating which will allow this update once complete

cartridge/cartridge-sass,code-computerlove/slate-styles