Simplify build process

The downside of this is cache-missing the entire extensions build phase once you add an entry to it

Author: jpcaparas

services/php/Dockerfile

@@ -4,38 +4,20 @@ FROM php:7.1-fpm
 RUN apt-get update && apt-get install -y \
 			libmcrypt-dev \
 			libxml2-dev \
-			libssl-dev
-
-# opcache
-RUN docker-php-ext-install opcache
-
-# zip
-RUN docker-php-ext-install zip
-
-# bz2
-RUN apt-get install -y libbz2-dev
-RUN docker-php-ext-install bz2
-
-# iconv
-RUN docker-php-ext-install iconv
-
-# calendar
-RUN docker-php-ext-install calendar
-
-# dom
-RUN docker-php-ext-install dom
-
-# mbstring
-RUN docker-php-ext-install mbstring
-
-# mcrypt
-RUN docker-php-ext-install mcrypt
-
-# mysqli
-RUN docker-php-ext-install mysqli
-
-# mysql
-RUN apt-get install -y libpq-dev && \
+			libssl-dev \
+			libpq-dev \
+			libbz2-dev
+
+# extensions
+RUN docker-php-ext-install opcache && \
+    docker-php-ext-install zip && \
+    docker-php-ext-install bz2 && \
+    docker-php-ext-install iconv && \
+    docker-php-ext-install calendar && \
+    docker-php-ext-install dom && \
+    docker-php-ext-install mbstring && \
+    docker-php-ext-install mcrypt && \
+    docker-php-ext-install mysqli && \
     docker-php-ext-install pdo pdo_mysql
 
 # mark volume/s as externally mounted