Update nginx to v1.13.5 and libressl to v2.5.5 (#8)

* Update nginx to version 1.13.3

Security: a specially crafted request might result in an integer
verflow and incorrect processing of ranges in the range filter,
potentially resulting in sensitive information leak (CVE-2017-7529).

* Fix dead link

* Change nginx to v1.13.4 and libressl to v2.5.5

* Change nginx to v1.13.5 and libressl to v2.5.5

* Fix docs

* Fix CI target branch

Author: Koki Yasuda

.travis.yml

@@ -4,7 +4,7 @@ sudo: required
 
 branches:
   only:
-    - devel
+    - develop
 
 services:
   - docker

Dockerfile

@@ -2,8 +2,8 @@ FROM alpine:latest
 
 MAINTAINER orleika <admin@orleika.io>
 
-ARG NGINX_VERSION=1.13.3
-ARG LIBRESSL_VERSION=2.5.4
+ARG NGINX_VERSION=1.13.5
+ARG LIBRESSL_VERSION=2.5.5
 ARG GPG_LIBRESSL="A1EB 079B 8D3E B92B 4EBD  3139 663A F51B D5E4 D8D5"
 ARG GPG_NGINX="B0F4 2533 73F8 F6F5 10D4  2178 520A 9993 A1C0 52F8"
 

README.md

@@ -1,15 +1,14 @@
 # Docker Nginx Image _(docker-nginx)_
 
 [![Build Status](https://img.shields.io/travis/orleika/docker-nginx/master.svg?style=flat-square)](https://travis-ci.org/orleika/docker-nginx)
-[![nginx](http://img.shields.io/badge/nginx-v1.13.3-blue.svg?style=flat-square)](https://nginx.org/en/download.html)
-[![LibreSSL](http://img.shields.io/badge/LibreSSL-v2.5.4-blue.svg?style=flat-square)](https://www.libressl.org/)
+[![nginx](http://img.shields.io/badge/nginx-v1.13.5-blue.svg?style=flat-square)](https://nginx.org/en/download.html)
+[![LibreSSL](http://img.shields.io/badge/LibreSSL-v2.5.5-blue.svg?style=flat-square)](https://www.libressl.org/)
 [![MIT License](http://img.shields.io/badge/license-MIT-blue.svg?style=flat-square)](https://github.com/orleika/docker-nginx/blob/master/LICENSE)
 
 > docker nginx image
 
 Small-Secure-Fast docker nginx image.  
-Base image is alpine, which is a security-oriented, lightweight Linux distribution. Most response headers are concealed, and DDoS mitigation is equipped. You should use secure headers included in `conf.d` for further safety considerations. Additionally, nginx caching parameters are optimized.  
-This image is automatically released by Docker Cloud.
+Base image is alpine, which is a security-oriented, lightweight Linux distribution. Most response headers are concealed, and DDoS mitigation is equipped. You should use secure headers included in `conf.d` for further safety considerations. Additionally, nginx caching parameters are optimized. This image is automatically [released](https://hub.docker.com/r/orleika/nginx/) by Docker Cloud.
 
 ## Install