Docker add simplexml

Needed for OPML import

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## 2018-0X-XX FreshRSS 1.10.2-dev
 
+* Bug fixing
+	* Fix Docker image for OPML import [#1819](https://github.com/FreshRSS/FreshRSS/pull/1819)
+
 
 ## 2018-03-04 FreshRSS 1.10.1
 

Docker/Dockerfile

@@ -3,7 +3,7 @@ FROM alpine:3.7
 RUN apk add --no-cache \
 	apache2 php7-apache2 \
 	php7 php7-curl php7-gmp php7-intl php7-mbstring php7-xml php7-zip \
-	php7-ctype php7-dom php7-fileinfo php7-json php7-session \
+	php7-ctype php7-dom php7-fileinfo php7-json php7-session php7-simplexml \
 	php7-pdo_sqlite \
 	php7-pdo_mysql \
 	php7-pdo_pgsql