changing sass precision to 10

see
twbs/bootstrap-sass#409
foundation/foundation-sites#4336
for examples of how the default precision of 5 causes rounding errors

Author: gxmikey

Diff for: lib/skins.js

@@ -61,7 +61,8 @@ module.exports = function (gulp, gutil) {
       .pipe(lr ? plumber()() : gutil.noop())
       .pipe(sourcemaps().init())
       .pipe(sass()({
-        includePaths: opts.includePaths
+        includePaths: opts.includePaths,
+        precision: 10
       }))
       .pipe(sourcemaps().write())
       .pipe(rename()(opts.skin + '.css'))