Add modules required by most of hacklab projects

Dockerfile

 FROM hacklab/php:7-apache
 MAINTAINER Hacklab <contato@hacklab.com.br>
 
-RUN curl -s -o wp-cli.phar 'https://raw.githubusercontent.com/wp-cli/builds/gh-pages/phar/wp-cli.phar' \
+RUN a2enmod headers \
+    && docker-php-ext-install pdo_mysql sockets \
+    && printf "yes" | pecl install memcached \
+    && printf "no\n" | pecl install redis \
+    && echo 'extension=redis.so' > /usr/local/etc/php/conf.d/pecl-redis.ini \
+    && echo 'extension=memcached.so' > /usr/local/etc/php/conf.d/pecl-memcached.ini \
+    && curl -s -o wp-cli.phar 'https://raw.githubusercontent.com/wp-cli/builds/gh-pages/phar/wp-cli.phar' \
     && chmod +x wp-cli.phar \
     && mv wp-cli.phar /usr/local/bin/wp \
     && wp core download --path=/var/www/html/ --version=4.9.1 --locale=pt_BR --allow-root \

README.markdown

@@ -69,3 +69,50 @@ to configure the section called "php-debug". It should look like this:
       Xdebug: false
     ServerPort: 9000
 ```
+
+## Modules enabled by default
+
+The modules below are used on most of hacklab WordPress projects and probably may be useful for wide range of projects. While modules can take a lot of memory for each Apache process, the modules below enable users to take advantage of a lot of WordPress Cache plugins, like _W3 Total Cache_.
+
+* apcu
+* calendar
+* Core
+* ctype
+* curl
+* date
+* dom
+* fileinfo
+* filter
+* ftp
+* gd
+* hash
+* iconv
+* json
+* libxml
+* mbstring
+* mcrypt
+* memcached
+* mysqli
+* mysqlnd
+* openssl
+* pcre
+* PDO
+* pdo_mysql
+* pdo_sqlite
+* Phar
+* posix
+* readline
+* redis
+* Reflection
+* session
+* SimpleXML
+* sockets
+* SPL
+* sqlite3
+* standard
+* tokenizer
+* xml
+* xmlreader
+* xmlwriter
+* zip
+* zlib