Fix Person.__repr__()

Change .lstrip("acct:") to .replace("acct:", "")

str.lstrip("acct:") strips all combinations of "acct:" from str
For example "acct:tactic@identi.ca".lstrip("acct:") returns
"ic@identi.ca"
Merge pull request #47 from kabniel/fixpersonrepr

Fix repr(Person) using replace not lstrip