chore: Dropped support of Node.js 4

Some NPM dependencies dropped support of Node.js 4. It is easier to drop it
too, that looking for workarounds to get the testing build running, or claim
the support without actually testing it.

Add testing opn Node.js 10.

BREAKING CHANGE: Dropped support of Node.js 4

.travis.yml

@@ -6,9 +6,9 @@ cache:
 notifications:
   email: false
 node_js:
+  - '10'
   - '8'
   - '6'
-  - '4'
 before_install:
   - npm install -g npm
 before_script:

README.md

@@ -16,7 +16,7 @@ The programmatic interface did not change and has remained compatible.
 
 ## Command-line usage
 
-Make sure that you have [NodeJS] >= 4 installed. Install the `nettime` package globally and print timings of a sample web site:
+Make sure that you have [NodeJS] >= 6 installed. Install the `nettime` package globally and print timings of a sample web site:
 
 ```bash
 $ npm install -g nettime
@@ -63,7 +63,7 @@ are compatible with curl. Timings are printed to the standard output.
 
 ## Programmatic usage
 
-Make sure that you use [NodeJS] >= 4. Install the `nettime` package locally and get time duration of waiting for the response and downloading the content of a sample web page:
+Make sure that you use [NodeJS] >= 6. Install the `nettime` package locally and get time duration of waiting for the response and downloading the content of a sample web page:
 
 ```bash
 npm install --save nettime
@@ -139,6 +139,7 @@ In lieu of a formal styleguide, take care to maintain the existing coding style.
 
 ## Release History
 
+* 2018-04-27   v2.0.0   Dropped support of Node.js 4
 * 2018-03-16   v1.1.2   Upgrade package dependencies
 * 2017-12-21   v1.1.1   Upgrade semantic release and other dependencies
 * 2017-11-11   v1.1.0   Support HTTP/2 requests

package.json

@@ -50,7 +50,7 @@
   },
   "devDependencies": {
     "codacy-coverage": "^2.1.1",
-    "codecov": "^3.0.0",
+    "codecov": "^3.0.1",
     "coveralls": "^3.0.0",
     "semantic-release": "^15.1.7",
     "standard": "^11.0.1",