Add support for mutiple PHP versions

[ashleyse2016]

Currently the Direct Admin addon only supports one PHP instance. Sometimes there are setups that use multiple PHP versions. We should be able to handle system setups that have 2 of these. The current setup uses /usr/local/bin/php, however we should also support custom locations like /usr/local/php55

[ju5t]

@ashleyse2016 /usr/local/bin/php is always there as it's what DirectAdmin uses. Can you let me know what I'm not seeing?