There was an illogical if/else statement that the "else" condition would always set a null value, so it didn't really matter. Re-wrote it to properly filter if the transport is set to dns srv and not affix the SIP Port to the server address.
Fix config URL so that the phones don't get an invalid URL when $domain_name is unset. They would previously receive `/app/provision` with no domain/ip included, which makes the phone unable to provision again once they have been added to the Devices page without manually re-setting the config URL or factory defaulting the device.
The alternative solution is that the PHP code could always ensure that the $domain_name variable is set even if the device doesn't exist. My suggestion is to see if it can be set to the same domain/IP as the original provision request from this unconfigured device
* Added the ability to pick the SIP account for the first two slots on each handset
* Revert to clean base
* Configurable firmware versions for Grandstream Devices
* Cleaned up duplicate P codes in gxv3504 prov, and spacing elsewhere
Updated or added configurable firmware versions to the remaining Grandstream configs
* Documented how to use the firmware version feature
* Formatting fix in Readme