Fix connector import

[tzzh]

I think that should fix #13 but I am not a go or a terraform expert and there a couple things I noticed that might be problems:

• if the actual config and the one in the the local terraform don't match it's going to succeed and then suggest the changes on the next apply which I am not sure is the behaviour we want
• It's also going to ignore config_sensitive which I think is fine as this is not something provided by kafka-connect
• I have also changed the signature of some of the functions to match what I saw in https://www.terraform.io/docs/extend/writing-custom-providers.html#defining-resources as it seemed reasonable and gave more meaningful errors when it was crashing initially

[Samlinxia]

@tzzh , I have the same error when importing existing resources. Will this patch solve this error? When are you planning to merge this? Thanks!

[Samlinxia]

@Mongey , thank you for responsive reply and merge.