Update Node supported versions to LTS

Author: Alvaro Navarro

.github/CONTRIBUTING.md

@@ -87,7 +87,7 @@ Travis will bow build the package and release it to NPM.
 
 #### **Do you want to contribute to the documentation?**
 
-Excellent, to get start developing this library ensure you have Node 6+ installed and clone the repository.
+Excellent, to get start developing this library ensure you have any of the [Node LTS versions](https://nodejs.org/en/about/releases/) installed and clone the repository.
 
 Then, you should be able to run the tests.
 

.github/ISSUE_TEMPLATE.md

@@ -22,5 +22,5 @@ __Stable Behavior?__ [What percentage of the time does it reproduce?]
 
 Please make sure you checked the following:
 
-* Are you running Node 6?
+* Are you running any of the current [Node LTS versions](https://nodejs.org/en/about/releases/)?
 * Did you download the latest version of this library?

.travis.yml

@@ -3,10 +3,9 @@ cache:
   directories:
     - "node_modules"
 node_js:
-  - 6
-  - 7
-  - 8.10.0 # explicit branch used for deploying docs
-  - 9
+  - 10
+  - 12.16.3
+  - 14
 branches:
   only:
     - master
@@ -20,11 +19,11 @@ deploy:
     keep-history: true
     on:
       branch: master
-      node: 8.10.0
+      node: 12.16.3
   - provider: npm
     email: [email protected]
     api_key: $NPM_API_KEY
     skip-cleanup: true
     on:
       tags: true
-      node: 8.10.0
+      node: 12.16.3

README.md

@@ -11,7 +11,7 @@ Amadeus provides a rich set of APIs for the travel industry. For more details, c
 
 ## Installation
 
-This module has been tested using Node 6 and higher, though it should work with Node 4 and 5 as well. You can install it using Yarn or NPM.
+This module has been tested using [Node LTS versions](https://nodejs.org/en/about/releases/). You can install it using Yarn or NPM.
 
 ```sh
 npm install amadeus --save