Use getenv instead of $_ENV.

$_ENV doesn't work if the user doesn't have E set in variables_order in the
php.ini, but getenv always works.
Always throw exceptions on SQL failures

We definitely want the default to be that an exception gets thrown if there
are any problems executing an SQL statement. If we need to ignore an
exception we can just catch it. Otherwise problems that happen because a
query fails don't get caught until way after the problem happens.
Default to default Apache log dir.

Apache has a variable you can use in the config files to get the path to
the log directory. So let's use that because without that it was trying to
put the logs in /etc/apache2/logs on Ubunutu.
Turn on exceptions by default.

This is a developer tool, so probably best to just have it show all the
exception information by default. The other alternative would be to raise the
verbosity level on the $output to OutputInterface::VERBOSITY_VERBOSE which
also shows stack traces, but I think this is actually nicer.
Now create automatically runs config if amp not configured.

When runing 'amp create' from inside another script it was erroring out
because I hadn't already run 'amp config'. This checks to see if the
mysql_dsn variable has been configured and if not, then it runs the 'amp
config' command which prompts for those vars.

I had to add an option to the create and export commands to let you output
the amp environment vars to a separate file to separate the prompts to
configure amp from the environment variable output.
Fixed error if output-file is not specified.

It can't be blank if you specify it, so don't specify it when we pass it on
if it is blank.
Added MySQL RAM Disk server.

This will setup a RAM disk and then run MySQL on it. To setup, just change
mysql_type: in services.yml to 'ram_disk'.
Apache vhost template - Generate logs for Ubuntu & MAMP