Fixing the php ext already loaded warnings

Example:
```
warning: exif (exif.so) is already loaded!
```

Author: winfried-van-loon

php-fpm/Dockerfile-56

@@ -114,8 +114,7 @@ RUN if [ ${INSTALL_MEMCACHED} = true ]; then \
 ARG INSTALL_EXIF=false
 RUN if [ ${INSTALL_EXIF} = true ]; then \
     # Enable Exif PHP extentions requirements
-    docker-php-ext-install exif && \
-    docker-php-ext-enable exif \
+    docker-php-ext-install exif \
 ;fi
 
 #####################################
@@ -147,8 +146,7 @@ RUN if [ ${INSTALL_AEROSPIKE_EXTENSION} = true ]; then \
 
 ARG INSTALL_OPCACHE=false
 RUN if [ ${INSTALL_OPCACHE} = true ]; then \
-    docker-php-ext-install opcache && \
-    docker-php-ext-enable opcache \
+    docker-php-ext-install opcache \
 ;fi
 
 # Copy opcache configration

php-fpm/Dockerfile-70

@@ -135,8 +135,7 @@ RUN if [ ${INSTALL_MEMCACHED} = true ]; then \
 ARG INSTALL_EXIF=false
 RUN if [ ${INSTALL_EXIF} = true ]; then \
     # Enable Exif PHP extentions requirements
-    docker-php-ext-install exif && \
-    docker-php-ext-enable exif \
+    docker-php-ext-install exif \
 ;fi
 
 
@@ -168,8 +167,7 @@ RUN if [ ${INSTALL_AEROSPIKE_EXTENSION} = true ]; then \
 #####################################
 ARG INSTALL_OPCACHE=false
 RUN if [ ${INSTALL_OPCACHE} = true ]; then \
-    docker-php-ext-install opcache && \
-    docker-php-ext-enable opcache \
+    docker-php-ext-install opcache \
 ;fi
 
 # Copy opcache configration

php-fpm/Dockerfile-71

@@ -113,8 +113,7 @@ RUN if [ ${INSTALL_MEMCACHED} = true ]; then \
 ARG INSTALL_EXIF=false
 RUN if [ ${INSTALL_EXIF} = true ]; then \
     # Enable Exif PHP extentions requirements
-    docker-php-ext-install exif && \
-    docker-php-ext-enable exif \
+    docker-php-ext-install exif \
 ;fi
 
 #####################################
@@ -137,15 +136,15 @@ RUN if [ ${INSTALL_AEROSPIKE_EXTENSION} = true ]; then \
         && make install \
     ) \
     && rm /tmp/aerospike-client-php.tar.gz \
+    && docker-php-ext-enable aerospike \
 ;fi
 
 #####################################
 # Opcache:
 #####################################
 ARG INSTALL_OPCACHE=false
 RUN if [ ${INSTALL_OPCACHE} = true ]; then \
-    docker-php-ext-install opcache && \
-    docker-php-ext-enable opcache \
+    docker-php-ext-install opcache \
 ;fi
 
 # Copy opcache configration