dependency updates

.travis.yml

@@ -21,7 +21,7 @@ addons:
         - libgsl0-dev
 
 before_install:
-    - nvm install 7
+    - nvm install 8
 
 before_script: "_ci/setup.sh"
 script: "_ci/build.sh"

Gemfile

@@ -2,7 +2,7 @@
 source "https://rubygems.org"
 
 group :jekyll do
-    gem 'jekyll'
+    gem 'jekyll', '3.4.3'
     gem 'jekyll-sitemap'
     gem 'jekyll-redirect-from'
     gem 'jekyll-picture-tag'

package.json

@@ -24,44 +24,44 @@
     "normalize-opentype.css": ">=0.2.4",
     "picturefill": ">=2.3.1",
     "simple-jekyll-search": "1.1.8",
-    "svg4everybody": ">=0.0.2",
+    "svg4everybody": "^2.1.9",
     "time-elements": ">=0.6.1",
-    "vex-js": ">=2.3.4",
+    "vex-js": "^4.0.0",
     "webcomponents.js": ">=0.7.1"
   },
   "devDependencies": {
-    "autoprefixer": ">=6.3.6",
-    "babel-core": ">=6.24.0",
+    "autoprefixer": "^7.1.2",
+    "babel-core": "^6.25.0",
     "babel-preset-es2015": ">=6.24.0",
-    "browser-sync": ">=2.10.0",
-    "chalk": ">=1.1.3",
+    "browser-sync": "^2.18.13",
+    "chalk": "^2.0.1",
     "concurrent-transform": ">=1.0.0",
-    "critical": ">=0.8.4",
+    "critical": "^0.9.0",
     "cssnano": ">=3.6.2",
-    "del": ">=1.2.0",
+    "del": "^3.0.0",
     "fs": ">=0.0.2",
     "gulp": "github:gulpjs/gulp#4.0",
     "gulp-awspublish": ">=2.0.2",
     "gulp-awspublish-router": ">=0.1.1",
     "gulp-cli": ">=1.2.2",
-    "gulp-header": ">=1.2.2",
+    "gulp-header": "^1.8.9",
     "gulp-htmlmin": ">=1.1.2",
     "gulp-if": ">=1.2.5",
-    "gulp-imagemin": ">=2.2.1",
+    "gulp-imagemin": "^3.3.0",
     "gulp-include": ">=2.0.2",
     "gulp-load-plugins": ">=0.10.0",
     "gulp-postcss": ">=6.1.1",
     "gulp-rename": ">=1.2.2",
-    "gulp-replace": ">=0.5.3",
+    "gulp-replace": "^0.6.1",
     "gulp-rev": ">=4.0.0",
     "gulp-rev-replace": ">=0.4.1",
     "gulp-sourcemaps": ">=1.6.0",
     "gulp-stylus": ">=2.3.1",
-    "gulp-svg-sprite": ">=1.2.2",
+    "gulp-svg-sprite": "^1.3.7",
     "gulp-uglify": ">=1.2.0",
-    "js-yaml": ">=3.8.3",
+    "js-yaml": "^3.9.0",
     "request": ">=2.81.0",
-    "yargs": ">=8.0.1"
+    "yargs": "^8.0.2"
   },
   "engines": {
     "node": ">=7.0.0"