Fix un-translateable text, improve block title generation code

I have found a couple problems in the user_relationship_blocks.module in a function that generates block titles.

1. The "My" in block titles that name a specific relationship type (such as "My friends" or "My professors"), is currently not run through the t function, and so cannot be translated.
2. The coding of the title generation function is perhaps overly complex, and unnecessarily runs some text through the t function more than once (first as component parts, and again as part of a larger concatenated string).

I have uploaded a patch as a possible solution that solves problem 1, and replaces the code described in problem 2 with a simple case statement.