moved to php7-alpine base image and initial clean up

Dockerfile

@@ -1,36 +1,16 @@
-FROM alpine:3.6
+FROM php:7-fpm-alpine
 
-MAINTAINER diego@passbolt.com
+LABEL MAINTAINER diego@passbolt.com
 
 ENV PASSBOLT_VERSION 1.6.5
 ENV PASSBOLT_URL https://github.com/passbolt/passbolt_api/archive/v${PASSBOLT_VERSION}.tar.gz
 
-ARG BASE_PHP_DEPS="php7-curl \
-      php7-common \
-      php7-gd \
-      php7-intl \
-      php7-json \
-      php7-mcrypt \
-      php7-mysqli \
-      php7-xsl \
-      php7-fpm \
-      php7-phar \
-      php7-posix \
-      php7-xml \
-      php7-openssl \
-      php7-zlib \
-      php7-ctype \
-      php7-pdo \
-      php7-pdo_mysql \
-      php7-pear \
-      php7-session \
-      php7-iconv \
-      php7-mbstring"
+ARG PHP_EXTENSIONS="gd \
+      intl \
+      mcrypt \
+      xsl"
 
-ARG BASE_NODE_DEPS="nodejs \
-    nodejs-npm"
-
-ARG PHP_GNUPG_DEPS="php7-dev \
+ARG PHP_GNUPG_BUILD_DEPS="php7-dev \
       make \
       gcc \
       g++ \
@@ -42,33 +22,15 @@ ARG PHP_GNUPG_DEPS="php7-dev \
       zlib-dev \
       file"
 
-ARG BASE_PHP_DEV_DEPS="php7-tokenizer \
-    php7-xmlwriter \
-    php7-simplexml \
-    php7-xdebug \
-    git \
-    openssh"
-
-RUN apk add --no-cache $BASE_PHP_DEPS \
-      $BASE_NODE_DEPS \
-      $BASE_PHP_DEV_DEPS \
+RUN apk add --no-cache $PHP_EXTENSIONS \
+      $PHP_GNUPG_BUILD_DEPS \
       sed \
-      tar \
-      bash \
-      curl \
       nginx \
       gpgme \
       gnupg1 \
-      recode \
-      libxml2 \
-      openssl \
-      libpcre32 \
-      mysql-client \
-      ca-certificates
+      mysql-client
 
 RUN apk add --no-cache $PHP_GNUPG_DEPS \
-    #https://bugs.alpinelinux.org/issues/5378
-    && sed -i "s/ -n / /" $(which pecl) \
     && pecl install gnupg \
     && echo "extension=gnupg.so" > /etc/php7/conf.d/gnupg.ini \
     && apk del $PHP_GNUPG_DEPS \