Versions parameter in katcp client and deprecated inform handling in inspecting client.

Some Questions?

1. Should the reported versions be string or list? I join the list into a string. [line 338 client.py]
2. Are we happy to remove "katcp-" form the version name. [line 337 client.py]. Feels natural/nice when using self.client.versions.library vs self.client.versions["katcp-library"]