Correct syntax for Python 3
Implement the 'oplogns' argument from mongooplog. Allows the tool to run on master/slave pairs where this tool can be particularly useful for migrations.
Refactor for flatter, cleaner code
Merge features
Create compatibility function for iteritems
Merge Python3
Extract construction of rename dict as a function. Use that function in the ArgumentParser. Leverage the rename dict in the main function.

--HG--
extra : amend_source : ef12b1c123673ef28b1e22a5c363adf335a09c97
Use MongoClient instead of deprecated Connection
Extract start calculation as function
Update _calculate_start for simplicity and conciseness.
time.time is sufficient for a UTC timestamp
Add oplog tailing technique as recommended by Bernie Hackett, author of pymongo.
Split out query_oplog and tail_oplog so they can be called selectively.

--HG--
extra : amend_source : e4176e8bbd09259e60ac5b936ca3d065608b43ef
Extract the op handler from the main function

--HG--
extra : amend_source : 4b5f191069231a4e40af9479169cd112eb56bb9e
Normalize indentation
Merge with tailable
Correct continue to return
Merge
Timestamp requires an integer
Merge