Minor fixes for server.py

2 commits:
1) get rid of pyc files (were committed into the repo for some reason)
2) Minor style fixes in server py
+= on strings in a loop is considered bad style (inefficient in long loops) the traditional python construct for this is
''.join(<some list or generator expression>)
colon without a newline is also controversial, usually if it's a single line thing, list comprehension should be used:
lst2 = [f(x) for x in lst]