Generic PHP docker container

Supported tags and respective `Dockerfile` links:

Environment Variable	Type	Default Value	Description
PHP_CLI_MEMORY_LIMIT	Int	-1
PHP_ERROR_REPORTING	String	E_ALL
PHP_TRACK_ERRORS	String	On
PHP_ERROR_LOG	String	/proc/self/fd/2
PHP_DATE_TIMEZONE	String	UTC
PHP_SENDMAIL_PATH	String	sendmail -t -i
PHP_MYSQLND_COLLECT_STATISTICS	String	On
PHP_MYSQLND_COLLECT_MEMORY_STATISTICS	String	On
PHP_FPM_ERROR_LOG	String	/proc/self/fd/2
PHP_FPM_LOG_LEVEL	String	notice
PHP_FPM_ACCESS_LOG	String	/proc/self/fd/2
PHP_FPM_CATCH_WORKERS_OUTPUT	String	yes
PHP_FPM_CLEAR_ENV	String	no	Not available for 5.3
PHP_FPM_LIMIT_EXTENSIONS	String	.php
PHP_FPM_MAX_CHILDREN	Int	4
PHP_FPM_MAX_REQUESTS	Int	0
PHP_FPM_PROCESS_IDLE_TIMEOUT	Int	30
PHP_MEMORY_LIMIT	Int	1024
PHP_MAX_EXECUTION_TIME	Int	300
PHP_MAX_INPUT_TIME	Int	60
PHP_MAX_INPUT_VARS	Int	2000
PHP_POST_MAX_SIZE	String	512M
PHP_UPLOAD_MAX_FILESIZE	String	512M
PHP_DISPLAY_ERRORS	String	On
PHP_DISPLAY_STARTUP_ERRORS	String	On
PHP_XDEBUG	Bool
PHP_XDEBUG_DEFAULT_ENABLE	Int	0
PHP_XDEBUG_REMOTE_ENABLE	Int	1
PHP_XDEBUG_REMOTE_PORT	Int	9000
PHP_XDEBUG_REMOTE_AUTOSTART	Int	1
PHP_XDEBUG_REMOTE_CONNECT_BACK	Int	1
PHP_XDEBUG_REMOTE_HOST	Bool	localhost
PHP_XDEBUG_MAX_NESTING_LEVEL	Int	256
PHP_LOG_ERRORS_MAX_LEN	Int	1024
PHP_IGNORE_REPEATED_ERRORS	String	Off
PHP_IGNORE_REPEATED_SOURCE	String	Off