2to3: Apply the `numliterals` fixer and skip the `long` fixer.

The numliterals fixer replaces the old style octal number like '01' by
'0o1' and removes the 'L' suffix specifying Python 2 long integers.

Octal values were previously mistakenly specified in some dates, those
uses have been corrected by removing the leading zeros.

Simply Removing the 'L' suffix should not be a problem, but in some
testing code it looks necessary, so in those places the Python long
constructor is used instead.

The 'long' type is no longer defined in Python 3. Because we need to
have it defined for Python 2 it is added to numpy/compat/np3k.py where
it is defined to 'int' for Python 3 and 'long' for Python 2. The `long`
fixer then needs to be skipped so that it doesn't undo the good work.

Closes #3074, #3067.