Update test/coverage packages

Author: simonbuchan

.gitignore

@@ -1,4 +1,4 @@
-/node_modules/
+node_modules/
 npm-debug.log
 
 /docs/

package.json

@@ -45,10 +45,10 @@
     "sjcl": "^1.0.3"
   },
   "devDependencies": {
-    "ava": "^0.16.0",
+    "ava": "^0.17.0",
     "babel-core": "^6.13.2",
     "babel-loader": "^6.2.4",
-    "babel-plugin-istanbul": "^2.0.3",
+    "babel-plugin-istanbul": "^3.0.0",
     "babel-preset-es2015": "^6.13.2",
     "babel-register": "^6.14.0",
     "cross-env": "^2.0.1",
@@ -58,7 +58,7 @@
     "eslint-plugin-import": "^1.13.0",
     "jsdoc": "^3.4.0",
     "mock-require": "^1.3.0",
-    "nyc": "^8.4.0-candidate",
+    "nyc": "^10.0.0",
     "sinon": "^1.17.5",
     "webpack": "^1.13.1"
   },