unifi_ssl_import.sh does not work for BYO cert

[joshuacameron]

From the merged pull request two days ago of #28

The SIGNED_CRT value is now entirely ignored, and in turn caused the script to create a corrupted(empty?) keystore, which in turn blocked the unifi web ui from loading. The unifi service still ran, but the web ui would not load. This parameter is important for people using their own certificate.

I simply used this, but I'm sure there is a more elegant solution
cat mydomain.crt >> mydomain-chain.crt

This was the error from the server.log which led me to figure out the cause.